First of all, ads and donations give me like 200€ a month. So that makes a profit of 130€ before tax.
Actually calculating the "running cost" is another story. A developers hourly rate is what? Something between 50€ and 280€? Doesn't matter.
What matters is that I spent thousends of hours creating and maintaining EDDB and it was never about the money. It was about having fun supporting a game I love.
Whoever comes up with any thought about money - it doesn't matter here! If we make a loss of 50€ or a profit of 100€ - this is a joke compared to actual developer costs. So whoever is continuing on this argument - nope, it's not our reality!
szopin eloquently explained the thing about money already, so I'm just going to ask: why did you do this now? Right in the middle of FDev running around fixing bugs with the game as fast as possible and a major event coming up this weekend? In my opinion, and the opinions of others the timing is really underhanded at best (Phoenix_DFire said it was sabotage at worst as well, on top of this/the last page, though I wouldn't go that far, going with scummy at worst) and you could likely have gotten the same results if you had done it at a more stable time, with less frustration on everyone's part. I would certainly be less questioning of your move (and any financial gains) if it hadn't come at the time it did.