Full disclosure - I've only gone to hackathons to accompany co-workers to provide advice and to network, I don't have any desire to actually participate.
Anyway, my general view on hackathons are they are a waste of time. If you want to learn something, learn by doing a real task, not a contrived one for a hackathon. If you are taking a more practical idea into a hackathon, sit on it, use that time to think it through, and build it on your own time, rather than in a noisy room. I get that people want to network, that they need motivated, and that constraints/goals/focus can inspire them, but I really feel that in software development, that's just people looking for an excuse. If you want to build something, build it. If you want a constraint, write it on a piece of paper yourself and follow it. If you lack the creativity to make something without the help of a hackathon, you are probably a lost cause anyway.
You can experiment with that new technology yourself. You don't need the group to tell you what you are doing is right or cool. The group is often wrong or misguided. History is full of bad group think. The way I see it is that if you are really a computer scientist, look at your computer and the world around you for a few minutes. You should easily see thousands of problems that need to be solved or can be solved better. It doesn't matter if it is polishing an old tech or a crazy new idea that throws out everything we learned before. I have more problems to solve than I can handle in a lifetime and I cannot imagine wasting that time at a hackathon in that kind of ridiculous environment.
You mentioned that there is definitely a bro/framework/money culture and I agree. Look at all the "schwag" and advertisements at most bigger hackathons. People want you to buy things and to use their stuff. Putting time constraints on people doesn't make them automatically more creative, often it just forces them into using whatever framework because of the nature of the hackathon so they can get something complete. This is constraining creativity usually, not encouraging it. This is not some romatic story about a lab deep in the bowles of MIT where the next great clean energy will save the universe, it is a gathering of guys trying to out muscle each other's egos. The bros will dominate because of this and will always be there in some form.
Check the experience level. Notice that a lot of great programmers don't go to these events. Why? They are working and don't really care, and nor should they. If you want to have some fun with people, start asking your colleagues and friends why they are going to XYZ events, hackathon, whatever. Strangely enough, most people I have asked can't explain and give reasons like free pizza, chance to win an ipad, or to hear a presentation about ABC technology. Is it worth losing a day of work or the weekend for that? Can you not read things in more depth at home or even just watch the video later? What is the point?
The point is perhaps to just participate in more group activities and feel part of something. There are similar reasons why people go to religious services, join fraternities and clubs, and post on message boards. People like meeting like-minded people. When a dominant sub-group emerges within a group, it becomes the group and usually drives out the fringes. I remember older and smaller versions of hackathons and meetups at people's houses, garages, etc. in decades past. It was really the same thing where bad actors eventually dominated, and perhaps for awhile there was a period where it felt fun, then stopped. Very little has changed, only scale and the way the same personality types manifest themselves in the context of the time.
Don't get discouraged by these people. They are everywhere, in every sub-culture. If they want to call themselves stupid terms like "hackers" instead of software developers, so be it. If companies want to be idiots and put up job ads calling for "rockstar programmers," just ignore them and take it as early notice that working there would probably suck. If someone wants to shove their glued frameworks in your face and claim they are awesome, just point out exactly what they have done and how simple, or better yet, just do something better yourself. You be the example, and you be the good guy.
But yes, you are right, I hate these people and I too feel they are unethical with stupid ideas that advance nothing. I think this shameful bubble of valuations of companies that don't really produce anything including actual revenue based on something real (ads don't count, sorry, if advertising would die and take 98% of the internet with it, so be it) need to die a quick death.