In a nutshell, because I feel like I can. I've done this for a long time, often at high intensity, and I'm feeling like it's time to do something else. Almost everyone will get to this point sooner or later, no matter how passionate they were when younger. The relevant part is that pursuing one's possibly-non-remunerative dreams becomes a lot easier when you're sitting on years' worth of income from working in tech. Quitting too early foregoes that opportunity.