I don't know how people do it. I had issues with this when I was very young. I figured at a young age I would either be some academic (2with all the strange pseudo-intellectual thinking I did uncontrollably), or I would have great difficulty surviving. I tried very hard to make the former the case, but it didn't work out. It's hard to explain to people how you can do research and write a thesis but you can't put sandwiches together or work a cash register at a convenience store. Nowadays I just try to calm the mind chatter through tv and sometimes gaming, and try to make sure I'm eating and showering.
Even if you can't survive in an academic environment, it doesn't mean you shouldn't study or that you can't enjoy learning at your own pace. Read as much as you can about topics that interest you, digest and think on what you've learned, be open yet critical about it, be curious. It's not a competition, and learning isn't confined to schools. In fact, your environment may be even better for learning than being in school because you're not distracted by mundane affairs.
I find that the psychological distress DP/DR has put me through, including having been on the brink of suicide multiple times, has given me immense insights. I almost consider it a gift (though it's more of a trade-off because I'm somewhat crippled when it comes to functioning in society) because it enriched my inner world and widened my vision as to how I see everything. Every time I've hit rock bottom, I've gotten up as a better and more insightful person. It's also given me incredible self-awareness. Through DP/DR I've learned to see that virtually every, if not every, aspect of life also has a good side, even if it looks bad on the surface level. DP/DR itself is not an exception: it is a gateway to personal growth. I suffer because of it every day, but that suffering is what makes me think and feeds into my growth.
DP/DR made me who I am today.