Agree that a maximum of 20-25% market share (so a 4 or 5 horse race) makes it a more fair fight, admittedly on nothing but vibes and experience. And markets without the competition require any majority holder to help competitors gain a foothold and create the competition. This would minimise desire to create monopolies as they would be forced into breaking them.

I know in practice this would never happen but I’m talking hypotheticals here.