Except in this example, there is nothing preventing other companies from building new roads. And in fact other companies have attempted to build new roads, competing by lowering the 30% fee to 10%, and even paying trucking companies to start using their roads. Except their roads are so poorly maintained that trucking companies choose to continue using the existing roads despite the higher fee. Also EA made some roads that went directly into the ocean for some reason.

This doesn't match with the definition of rent-seeking at all, as described in your wikipedia link:

> Rent-seeking is the act of growing one's existing wealth by manipulating public policy or economic conditions without creating new wealth.

To my knowledge, Valve has not manipulated public policy or economic conditions to maintain Steam's dominance. Steam hasn't pushed for legislation to prevent competitors, it hasn't prevented developers from selling their games on other platforms, and it doesn't even prevent you from installing non-Steam games on Valve's own proprietary hardware and operating system.