Sustainable income as a gamedev?

Just a question that has been on my mind lately.

I've seen solo devs and entire teams on various media spending 6-12 months or more on a game and get a gross revenue of about 2-6K usd.

Now I'm by no means well paid where I live but it's not more than my monthly salary. I couldn't even pay my bills for a month with 2K net.

How do these people keep a business running?