It's worth emphasising that a great deal of work in unnecessary for improving net happiness and consumes resources in the process and so undermines long term prosperity.
So why have a Star Fleet? Because Jean Luc Picard is a Federation citizen, and he wouldn't be happy as other than a starship captain. It's a galaxy-spanning Potempkin village to make him happy. Why would they do that? You're thinking like a poor person. Think like an unfathomably rich person. They do it because they can afford to. He might have had a cheaper hobby, like say watching classic TV shows, but the Federation is so wealthy that Starfleet and a TV set both round to zero.
This makes Star Fleet officers into in-universe Trekkies: a peculiar subculture of the Federation who are tolerated because despite their quirky hobbies and dress they're mostly harmless. Of course if you're immersed in the subculture, Picard looks like something of a big shot. We get that impression only because the camera is in the subculture, not in the wider Federation, which cares about the Final Frontier in the same way that the United States cares about the monarch butterfly: "We probably have somebody working on that, right? Bright postdoc somewhere? Good, good."
Post-scarcity doesn't mean post-danger. No one has to do luge in the Winter Olympics to survive, and not more than 4 years ago someone died doing it, and yet people continue to do so.
It naturally follows that Earth was never in serious danger at any point because, hah, are you insane? We just didn't hit the Borg cube with the Lance of Judgement and instakill it from half a galaxy away because that would have been a terrible affront to Picard's character arc, and we really care about that sort of thing. Look at our Prime Directive: we'd rather genocide an entire race than interfere too much in the story. (Heh, psych, we're not total psychos. The Prime Directive strikes a few chords with our culture, because it needs to sound plausible to Starfleet officers, but isn't our main guiding principle any more than the US is based on not violating a shot clock. The Prime Directive is actually just there to provide interesting moral situations for Star Trek officers. We wargamed out several hundred generations of officers on a Holodeck simulation and they end up tremendously unfulfilled when doing the right thing is obvious, possible, and successful, like it always is in real life in the Federation.)
That is a beautiful, beautiful thought and plot device for a Sci-Fi book. Thank you for placing that into my mind.
I love it.
There are strong hints in Iain M Banks' Culture series that a significant portion of the mission of Contact and Special Circumstances is giving humans with a pathological need for conflict and excitement something to do to keep them happy.
In-universe evidence: despite being in a reality with infinite numbers of capricious demigods, Earth isn't dead yet. This is because Earthlings are essentially capricious demigods by the standards of more primitive cultures, but we really enjoy slumming it.
But it's also possible that robots have saved the Federation as many times as human-captained ships. I'd rather believe this than that it's because of the spirit-killing Section 31 being sneaky assholes behind everyone's back.
There are many enemies in the universe so Star Fleet is important. To name a few there are The Borg, The Makers, The Cardassians, The Romulans, And even the Klingons who are federation members.
War-like cultures would still exist even if the Federation believes they themselves have moved beyond that type of thing.
Yes, but they're not enemies like Nazi Germany was an enemy, or like Al Qaeda was an enemy, or even like Bonnie and Clyde were enemies. They're enemies like a hornet's nest is an enemy. (If you're really cynical, they're enemies like the Protoss are an enemy, seen from the perspective of an American playing Starcraft. They exist to make your universe more fun.)
Think of how far ahead of the Klingon Empire the Federation is. They routinely have a single man with delusions of grandeur outwit the entire Klingon race and nobody thinks this is odd. We know that in the logic of the Trek universe if it's the entire Klingon High Command personally at the helm of 100 warbirds versus Wesley Crusher and his high school science project that Wesley is destined to win, right? You don't even need to see the universe from the outside to come to that conclusion. Ask a Ferengi to handicap that contest. He'd tell you "Rules of Acquisition #47: never, ever, ever bet against the humans. There's no profit in it. Ever."
Think of some power multiplier, X, for demonstrating the geometric mean between civilization's level of ability to effect their wishes on the cosmos. Multiplying the Aztecs by Xs gets you the colonial Spaniards. Multiplying the Spaniards by X gets you the US. Multiplying the US by X gets you the lowest starship captain ever depicted in the series. Multiplying them by X gets you to the Klingons. The Federation is still several powers of X beyond them.
This implies that the Federation could probably wipe out everybody else with a for loop, and probably consider that low-intensity conflict resolution. But that wouldn't be fun. Why hit the Borg with the Lance of Judgment when there are still so many stories to tell about how Picard proved that passion and ingenuity beat raw technological dominance? The Federation loves such stories as only a technological superpower can.
An alternate take compatible with patio11's irreverent theory: war-like cultures exist only in the sense that some cultures have different LARP preferences.
Supporting evidence: how did the Klingon Empire (who are not actually part of the Federation) make it through their nuclear age without blowing up their planet? How do they continue to keep pace technologically with other species? They steal a lot of technology, e.g. they never invented the warp drive themselves, but that would only get them so far and wouldn't keep them competitive with the Federation.
Patio11's oddball theory of Star Trek as a documentary about a future LARP may not be correct, but it explains away these kinds of questions better than any "real" theory that I've seen!
Also I thought the Klingons were part of the Federation at one point during DS9 era? Or perhaps that was just an alliance...
There was indeed a military alliance between the Federation and Klingon Empire against the Dominion. A friend of mine (uncharitably) referred to the war against the Dominion arc as the writers, "exploring what Star Trek could be... if it was more like Babylon 5."
The sun is always in the same spot. It's always day. You can't see the _stars_.
Give me the surface of a planet, anyday.
I am neither advocating nor rejecting a basic income as a solution, but you can use it as a thought experiment to consider this. If people didn't need to work, why would they do things that consume resources and make us less happy?
The culture our kids grow up in (through media, educational institutions, community support, etc) is not particularly good at this yet. The work we can do on the internet is to translate phenomena into data, stories, and experiences that build awareness of problems and build skills to solve them.
The typical person is closer to Homer Simpson than to the intelligent, long term thinking and rational decision making individual.