As is it wasn't already obvious, hats are hugely profitable . Back in July 2013, we learned that workshop creators have collectively earned $10 million from their items . This week, on day two of the Valve-hosted Steam Dev Days event, the company announced that content creators made $400,000 in just the first week of 2014.

Here are some more mind-boggling stats that were posted to Steam Database :



484,768 compendiums were sold during The Dota 2 International, which added an additional $1.2M to the prize pool. (This is higher than the $1 million figure we've reported on previously ).



More than 90 percent of Team Fortress 2 content is from the community.



Valve reports that 17 million Team Fortress 2 accounts own items, with 500 million total items.



The Counter Strike: Global Offensive community has created 4700 maps and 20,000 weapon skins.



Portal 2 has over 381,000 user generated maps, which Valve attributes to the easy to use map editor.



Garry's Mod has a total of 250,000 user generated items.



Skyrim has over 19,500 pieces of user generated content.



As we wrote about back in November, microtransactions and free-to-play games may make developers a lot of money, but remain controversial among many players, who often feel like they are being nickel-and-dimed. The most recent, obvious example of this is Forza Motorsport 5 for the Xbox One, which had to reconfigure its in-game economy after and outcry from the community about the pricing on certain cars.

What's interesting here is that Valve has managed to sell the same type of content—optional and largely aesthetic—without alienating the player community. In fact, according to Steam Database, Valve's presentation at Steam Dev Days plainly stated the company rejects the idea that microtransactions must have a negative affect on the player's experience.

The trick to not angering the community, according to Valve, is to let it take the lead on this type of content. “User generated content is a vision of the game not restricted by the developer's resources,” it said. “People are going to mod a successful game anyway, so it's best to help them out and improve it for everyone."

According to Steam Database, Valve's presentation also stated that user generated content is the very thing that differentiates games from other media. It gives players a way to express themselves and improve the game for other fans, something we can't do to movies or books.