The deal with that Steam takes 75% is ok. It's ok for them to sell the mods.
I see nothing wrong with it at all.
Cosmetics for Dota 2 and CS:GO. The makers get a cut of it. How much I have no idea. Dota 2 tickets for tournaments. 15% goes to the pricepool. Volvo takes 75% of the total of it. So they get 10% to spend on the tournament itself. You can still watch the games for free on twitch. Its to support them why they do it.
The problem I see with how Steam does it is that they remove the donation links in the descriptions...
Edit: NOW STOP FUCKING CRYING ABOUT IT FFS.