I'd say it's more of a 'de facto' monopoly, as every other storefront sucks so bad.

It's ironic that Valve doesn't have shareholders forcing horrible decisions that make people hate a platform to maximize short term profits, yet they reap in crazy amounts of money per year in comparison to public companies with dogshit monetization. Funny how that goes huh?

Usually steam is mostly praised for being a decent company. But what are the devs saying about the 30% cut. Do they think it's reasonable or is there any discontent among the devs?

The number of people in this thread claiming that Steam is not a monopoly is too damn high. If actually you’re interested in the evidence, the Organized Money podcast recently had a great interview with pair of lawyers whose full time job is suing Valve as a monopolist on antitrust grounds, and winning over and over on behalf of their clients.

This study is just asking managers, they didn't talk to devs. Also how is it a monopoly when 80% expect to be using non steam distribution channels in 5 years? Maybe I'm missing something because the source study isn't available without giving them your name and email but their stats look contradictory to me and their method is... Well corporate managers aren't really devs IMO.

https://rokky.com/pc-game-distribution-report-2025

72% of devs have no clue what the word monopoly means. That would mean that Steam is the only store selling PC games on the market, but that's not the case. Hell, the article itself mentions several:

However, it also noted that developers have started utilising other platforms including the Epic Game Store and the Xbox PC Games store.

Almost half of those surveyed (48%) have distributed a title to both stores, while 10% have used GOG and 8% have used Itch.io.

So, a monopoly? Most definitely not. A market leader or holder of a vast majority? Yes.