"The fsf receives every year a substantial amount of money as an income."
Ha! I don't know which FSF you're looking at. $450,000 (okay, they ended at $461,000 at their last fundraiser)? For a staff of 12 people? That works out to about $38,416 per person. That's not a lot in the U.S. And it's even less if you add more people like you want to do. And that doesn't include office expenses like rent and whatever other costs there may be to keep the office going. Or running the LibrePlanet conference. I understand that MIT donates the space but it can't all be free. And other operational expenses throughout the year.
