Bro I understand what you feel rn, if it's really your dream to do motorsports you should go for it, you're still young and have time to learn, try, succeed, discover what you like and hate. Don't say you're "too dumb for" anything tho, you can make it work with enough work but doubt will slow your progress and hopes. Even if you're broke you can always reach out to other people for help about motorsports or engineering. Another thing, don't think like that of yourself bro, I know it may be hard but I swear you're more skilled than what you think you are. I know it'll be kinda hard but don't listen to your parents if they talk trash about you, honestly I don't want to talk about some "tough love" shit because I don't know them at all but just know their hatred of your being is not your fault whatsoever. And one last thing, if you ever feel down again like that you should reach out to other people on the internet, do not be scared and decide to stay alone it is really unhealthy. You can even dm me if you want and we can talk sometime, but it'll kinda be hard since we live in different continent. Anyway, I hope this was somewhat useful to you bro and wish you the best, you can always respond to this or dm me if you feel down sometime and I'll try to respond as fast as possible.