Why are you trying to do all or nothing? Start bootstrapped, focus on generating revenue, then quit your job. IndieHackers is a great site for this, their podcasts in specific are worth a listen to see how others did it [0]. Filter by "Indie Hackers" on the left sidebar, they have a few series but I'm talking about this series in particular which has interviews with those already making some amount of money and they're asked how they started.

[0] https://www.indiehackers.com/podcasts