I don’t have a great success story, myself, yet. But there certainly exists a plethora of self taught people that became developers. I don’t know what online courses you’re using, but some are great, some are terrible. I’ve gone through paid ones on a few different sites, and have watched tons of youtube videos. I also read articles, reddit posts, and books(thriftbooks has some cheap comp sci text books).
The #1 thing to becoming a successful developer is simply practice though. You’ve gotta just build shit.
I’m almost 22, have no college education, and have spent about 3 years teaching myself programming. I’m currently still only a hobbyist/indie dev. But, a few weeks ago I had a major tech company recruiter reach out to me, and i’ve got a preliminary interview in a few weeks. I’m hoping to become a self taught success story.