Interesting pattern emerging, the IT time of the admins is pretty damn priceless, (thank you admins!) but when an instance gets up to scale a lot of them can end up with a hard cost of 10 cents per user per month.
The last stat I remember from Facebook was revenue per user per year was around 4 dollars. At 31b revenue and 2.7b monthly users, Youtubes average profit per user is about $10 per user per year. 100 million people pay for YT premium now.
So if every user paid $1 per month, it might not pay all the costs but the admins could get paid something and the fediverse could scale. The bigger you get though, you get economies of scale from future Fediverse data centers, but also you need really good programmers because its a huge temptation for hackers and propagandists.
I also want to say its a labor of love and a lot of work for mods too who may be non technical but the work and time they put in is important.