There's something I call The Manteen Ghetto
It's where adult men, ages 18-48, continue trying to act like children. They do this to defer the questions of life. When you realize society is fucked up, and you don't want a part of it, you have three basic choices: say nothing, become an "activist" outsider who agitates to destroy it, or join it -- and then change it from within.
Of course, we all know that "I'm Changing It From Within" is an excuse for many. I'm changing it from within -- by buying this Mercedes-Benz. But... what idea cannot be inverted by hipsters, who use it as a justification and not a reason why? There are ecofascist hipsters, too. Traditionalist hipsters. Anarchist hipsters. National Socialist hipsters. Zionist hipsters. Zoroastrian hipsters. Rastafarian hipsters... the list is infinite, because any idea can go from being an "end" (abstract, ongoing goal) to a "means" (justification for an existence of poverty and self-indulgence, hiding one's ordinary unexceptional disillusioned underachiever-ness).
In contrast to joining humanity, gaining power in society, and using that to influence people closer to truthful ideas -- a process called kaizen or incremental improvement as a method of design -- activism and shut-in-ism allow you to drop out. Over time, even if your original motivation was to change the world, you find yourself falling farther away from what anyone can relate to, and so you start using your Motherfucking Important Ideology (MII) as a justification and not a reason why. Soon you're a hipster by accident, but a hipster nonetheless.
Joining society takes some balls if you're not going to compromise your ideals, but life was never made for fence-sitters, nancypants, metrosexuals and emos. Joining society requires that you join your ideology to action that also makes itself pragmatic. You live for something outside yourself: family, friends, culture, heritage and ideology, all together at the same time. (And I don't include in this the odious hybrid of "activist businesses" like eco-coffee and vegetarian restaurants where you pay what you think you owe... the only good examples of this, like Rutamaya Coffee and Ben and Jerry's Ice Cream, put business first.)
It's easier, actually, to live for something outside yourself. That way, when you act, you're not acting selfishly, but to assert a positive order around you. Family. Community. Eugenics. Art. All of these fit those profile.
Your alternative is to be one of those people who has fallen into their own self-conception, and is now using the external world to try to create a self-identity. E.g. a hipster.
These people strand themselves in The Manteen Ghetto. They act like teens, but are grown men and women. They use art, music, ideas, etc. to justify themselves, to hide the fact that they're living lives of pleasuring themselves alone and are not contributing anything. They are the opposite of living for something outside the self, like joining society so you can have a family, a career, and power and influence to enact your ideology. They're drop-outs.
What does it mean to mature past teenage years? Back to living for more than yourself.
You start to realize you're a gradient. From the time you are born until death, you're slowly eroding. If you make it to old age, you slowly erode before you die, and then at some point, death is a release. So it goes. But you need to plan for the whole lifespan, and you start to see how acting like a teen will be stupid. So there's a 65-year-old hipster next door who's still really into punk rock... pathetic. He dropped out, and now he wants you to see how cool he is so he feels better about having nothing in life and having influenced nothing, because he has nothing. Food is wealth, wealth is power, and power is how you change ideas... changing ideas is how you make society better without you and fifteen hundred of your grubby friends grabbing rifles and rushing at the gov't troops.
You also start to realize that the best rewards are outside the self. Like making change, making a family means you're populating earth with better people. Only idiots say "don't breed" to the best and smartest nations on earth. Only idiots insist that, because they are retarded, everyone must be and so they should not spawn. If you've got a brain, find someone else with a brain, and make more beautiful, smart kids. Fuck the doubters. Like making change, contributing to your community -- gaining power, having people trust you and your wisdom, and thus having Memetic Influence -- means you're living for more than yourself.
There are many ways to start. I know that many of you will offer up that tired modern excuse I'm Busy but I'm sorry to tell you: you're full of shit. Every person I've known who was heading anywhere in life spent some time in unrecognized volunteer efforts. Even when they were in graduate school, launching careers, etc. "I'm Busy" is a coverup for your own disorganization, or your pursuit of dead-end self-stimulus, like masturbating, video games, movies, etc. You can sacrifice some of that time and you won't miss it, because you'll have replaced a closed-circuit reward with an enduring one.
Things that unite the self and the world are rare, but they are fulfilling, and make you regret death less. Family, culture and healthy activity come to mind. Working for ANUS also comes to mind: it's something you can do for a few hours per week or day, see immediate effect as healthier memes dominate over shitty ones, and gain experience you'll use your whole lifestyle.
Anything else is an excuse to remain in The Manteen Ghetto, pleasing no one but yourself, and being correspondingly empty as a result.