I don’t see a cogent argument here. Valve is providing exactly what they say they are, money for a service, and very convenient too.
Valve doesn’t prevent games from being sold elsewhere, they don’t enforce exclusives.
This is like saying Costco is ripping me off because it won’t stock coke if the price would be higher than sam’s club.
Most people don’t know what a phone app actually is.
That is 100% true