Customers flock to valve because it's more than a storefront. It eliminates the needs for everything else, no need for discord, forums, lfg pages, recording software, controller mapping software, 3rd party mod hosting, mod managers, etc etc etc. look at how much further Valve has pushed Linux and Linux support in gaming than anyone imagined possible. Look at their return policy, absolutely no other storefront is that consumer friendly.

30% is industry standard, get mad at the storefronts that are just storefronts as well as steam or you're just sounding like Tim Sweeney on another unhinged nepo baby rant.

Because they provide a lot of value.

It's not like GoG or EGS are better stores that can't get traffic.

In fact, if anyone actually put enough money and created a store with better moderation, people would be more than happy to use it. It's just that there is none. Not because they lack users, but features.

their monopoly on the market

Should Steam be doing something differently in order to not be a monopoly? Their competitors being shit doesn't make Steam a Monopoly.