I really wish there was a way to: (a) have the autonomy and interesting work of a startup tech founder (while a full-time technologist, not a manager) but (b) without the extreme income variance. If your job requires you to take personal loans, there's something wrong. I also think there are a lot of people who have the talent but not the ability to afford the risk. The extreme income variance is a bug, not a feature…
you are looking for a rose without the thorns:) you'd be better off with a lily ( ie. straight job at big-co/small-co, no income variance )
Career capital is basically how much a company values you. You can more or less trade career capital for things like money, promotions, freedom, etc.
Different companies will let you trade career capital for different things. Small startups generally grant more autonomy and less cash. Investment banks will let you get plenty of cash, but all the career capital in the world won't buy you autonomy.
The mistake most people make is that they don't consciously invest their career capital. They take raises and promotions when they should really be negotiating for more freedom and interesting projects.
If you want to love your work, figure out
1. How to become extremely valuable and earn lots of career capital,
2. What you want to spend it on. There is usually a constraint in your life-feeling that you don't have enough freedom, enough cash, etc. Spend your career capital on your biggest constraints.