I was fairly good at BMX racing in my teens/20's. Got flowed parts/support from some companies but never made any money from it. I have some good friends that were pros for years and made a good living but I could never quite reach their level. In these action sports industries like BMX, snowboarding, and skateboarding a lot of sponsorships are about who you know. The list of dudes I've ridden with over the years who are insanely talented that can ride the fuck out of their bike never get a shot because they were never introduced to the right people is a mile long. If you live in LA, San Diego, Austin, or central Florida you're more likely to get noticed because many of the brands that make BMX goods have their headquarters in these areas. They sponsor events, the pros live in those towns, and so they don't have to go far to scout talent.
I'm 40 now, I still ride on the weekends and again, I'm fairly good and not just for my age. I have a chronic autoimmune condition that keeps me off my bike from time to time but I still try to be consistent when I'm feeling well enough.