Less than 5% of indie startups manage to make more than $1 million gross revenue from games as per some public statistics.
The majority of solo indie developers and micro software houses have a very low gross revenue from games although it’s pretty easy to break the $100,000 Personal license gross revenue margin set on FAB.
In Europe taxes are 50% or higher in most countries so selling games is not an easy way to become rich unless a game manages to sell many copies. But most indie games either are a market failure in the 20,000 or less copies sold or manage to make enough money in the 50,000+ copies sold. In both cases are still enough for a living but not for being rich. And it’s not that solo indie developers and micro software houses manage to become rich after 1 or 2 games sold. It rarely happens. Few can aim to become a small to medium software house in a few years and most stop to exist or solo developers keep going on their own and never can grow in gross revenue… which means selling 10,000 or 20,000 copies of each new game and not getting any game to 50,000+ copies sold.
Then there are the lucky ones that manage to sell 100,000+ copies but most just don’t.