CervelloYM: With extra 5 euros you can own the game instead of renting it. Isn't that already great?
You get a license either way, GOG's license and service are just superior. The rightsholders own the games.
Braggadar: Because, like all businesses that have existed since mankind has been selling goods to one another, a business sets what price it considers it needs to make a profit, stay competitive and stay afloat. When and how often it runs sales is part of this.
Steam is massive and can afford to undercut its competitors. Key resellers are an extension of this effect.
Steam does not set prices and does not undercut anyone. The one thing they do demand is that the rightsholder should not undercut Steam.
Damon18: Humble Bundle?
Do you mean that public library that sells only books and comics on sales in the last 6 months?
They had the complete Crusader Kings 2 for $15 just two weeks ago.