I actually think it’s the exact opposite and Epic would have picked a fight with Apple even if the fees were 15%.

This isn’t about fees and it’s not even (just) about Apple - Apple is just a relatively unsympathetic defendant for them to fire their opening shot. As noted, Microsoft fees are 30%, Google fees are 30%, etc, and yet Apple was singled out (with those companies actually jumping onto the lawsuit against Apple too).

This is, more generally, about prying the Apple platform open, and other similar platforms like it. Remember, Epic didn’t start this suit over anti-steering clauses, the real goal here was epic getting their own third party store, which means they don’t have to pass an Apple review before being able to request permissions that let them mine data/etc. Thats a way bigger prize than (checks notes) 30% of 12 million dollars.