About the only places I'd call actual competitors... Are none. Nobody is close to 10% of Steam sales and specialized in video games. They are a monopoly and will push the price. They cannot push it too much or a cheaper small store might overtake them, but competition is not the force setting the price. The cost of switching is. The network effect strength are.

Maybe someone in China could, but they don't directly compete.

GoG has a niche they're trying to expand, as does Humble. A few other small stores. Game company ones (EA, Blizzard, Ubisoft) are not even close. Funny enough, the small shops often resell Steam keys...