This topic comes up frequently on this forum, and it annoys me...
Whether it's Smash or video games in general, there should be no "retirement" age. I realize we haven't yet gotten to the point where most older adults had video games when they were younger, but that doesn't mean "Once you turn 20 you're not allowed to play video games anymore". Yeah, you've got a career when you're older, but it's not honestly as if you have endless free time when you're still in school either. Just because you're now making your own living doesn't mean video games are/should be prohibited. It's just that being a gamer is fairly socially unacceptable even as a teenager (well, unless you're playing Wii Sports/Tetris), so it's even more socially unacceptable to legitimately play video games when you're out of school. And people are still falling for society's stupid restrictions.
I've got a piece of advice for you: if you really care what society tells you is acceptable and not, you should probably leave this forum now considering it's really not socially acceptable to be a regular on a video game forum and play a video game competitively.
If you don't, then quit playing Smash/video games when you're bored of them and not a moment sooner.
/rant