It’s not leeching, Valve mostly lucked into this monopoly because of how grossly incompetent competition was at the time. Valve owners were rewarded handsomely for this already, there’s no reason for this to continue until heat death of the universe because there’s not that much value added that they provide now.

It’s cool that they pay salaries of like 3 Linux devs and piggyback on Wine work that Codeweavers funded for the past 30 years. You’d think there’s so much more they could do with 30% cut of nearly all PC game sales however which is why they need competition.

Details of such breakup can be ironed out but it’s important to keep in mind that this option exists and was used before successfuly.