There are still FLOSS projects that still have that hacker culture you mention. You can still build things and feel good, though you probably won't get paid. Check their mailing lists, Github issues, IRC chats, Slack or whatever channel these projects use for communication, there are big discussions in what technical decisions to take. These projects always need help and also have different problems to be solved.

It might fill that gap you have (at least it did for me).

In the end you will see your job just as an income source but most of your passion will be in contributing to FLOSS projects, if you get paid for contributing to FLOSS even better.

You mention those 80s 90s hacker ethos, be like that, be curious, try checking someone's else code, play it with, read what things need to be improved, hack it and show it.