LOL! What does age have to do with investing in bitcoin? You only need money to invest. And usually young people have less money and less patience than older people, so the older you get the better you'll become at investments not the other way around.
I mean, age is indeed a factor when investing in general. If you're closer to death then risking money onto a volatile asset such as bitcoin might not make that much sense. On the other hand? 28? Lol. OP has a pretty long runway unless he/she isn't taking care of him/herself.