You think a PhD will be more fun? Everyone I know who has done a PhD is usually whining about it.

Also… spreading thin is what everyone does, until one day they decide to focus on one thing.

What stops you from having an internship and working on your project at the same time?

Well instead of sitting writing this question on Reddit… you could be working on your project. Or are you doing it during business time?

There’s no stability in startups. Heck, there’s not even stability with a permanent position in a big company. Maybe 50 years ago

Why not shuffle your other costs? Stay somewhere cheaper and keep getting the high paycheck to build emergency funds if you don’t have.

Well the point is that you have control over your work. You can ditch a client if you don’t like working there… you can have gaps between gigs without the need to tell anyone, etc.

Maybe you should consider working on short-term projects or part-time.