For much of my life, when we spend money on space, we get not-space.
For the money we spent on the X-30, X-33, X-34, and X-38, when Dan Goldin was NASA administrator, what did we get? Not-space. (At least the X-37 is up there spyingflying.)
The orbital space plane program, the one that was Sean O'Keefe's thing - neat plans, more capsules than planes IIRC, but ultimately we got not-space from it.
The Vision for Space Exploration, under Michael Griffin? Rocket designs that were approximately equivalent to throwing your astronauts into a paint mixer. A system about which the review panel said that "If they gave us the system on a silver platter, the first thing we'd have to do is cancel it, because we couldn't afford the ongoing costs." A lot of money, a launch pad rusting in the Florida weather, and a whole lot of not-space.
And for all the money we spend on human spaceflight, we now send Astronauts up as passengers in Soyuz rockets.
Now we're spending $18 billion dollars - figure subject to change, always upward - to build the SLS - the Senate Launch System. (Another estimate has it at $40B for development and the first 4 flights.) If all things go as planned, it will launch once every two years, launching an unmanned trip around the moon in 2017 and a manned trip to the moon in 2019. Schedule subject to change - always slipping.
Does anyone thing that SLS has a chance of working? Or is it just going to become another not-space program?
How about the replacement for the Hubble Space Telescope, the Webb Space Telescope? In 1997, it was going to be launched in 2007, and it was going to have cost 500 million dollars. Now we've spent 3.5 billion on it, and it will launch in 2018. Maybe. That's a ton of money to spend on not-space - and it's money that's been taken away from the moderately successful bits of NASA, like the Mars program, which doesn't have a mission in it after 2013's MAVEN.
I don't mind spending money on space. I like space. I've been following the MER rovers for nearly a decade. I think COTS and Commercial Crew are brilliant, and hope that they will continue to exist with a program structure that rewards results, rather than existence. Commercial space is the last best hope to get a domestic space capability.
But times are tight. We're massively overspending as is - borrowing tons of money our grandchildren will still be paying back. So increased spending is far from free.
Is it worth it? I say yes. Spend money on space. Where do we get that money? Let's stop spending it on not-space, like we have been.