Earlier quoted context omitted.
I seriously doubt the lead developers of a team of 4 make more than $11k in most of Europe.
It's hard to compare between different countries due to different taxes and so on. But that's almost double what a generic team lead would make here in Sweden (50-60 is probably closer) but a high level dev working a prestige project could make more of course. They should probably change the business model to make more money from consulting or lecturing. Many companies pay well to get "famous-project" devs for consul…
Of course, the drawback is that the project would need even more devs to compensate for the time giving workshops, so IDK whether it would work out in the end.
The salary is high for Europe, but not outlandish. I come within 15% working in IT in old industry but without leading a huge project and managing people, cooperation and giving talks. So, no, they should not pay much less even if the contributors probably have their dream job in contrast to me.