Better drop Rates at higher stages

I just think a way to incetivate people to spend more money into the game is give them higher chance to get better rewards as they advance in pve. As example, if u're at chapter 2 stage 1(2-1) u will have like 75% to drop equipments and 25% to drop skin or weapons, if u're like at 12-10 u have 50%/50%. Going further we can change de rates of stars too, using the same analogy u will have like 90% to get 3 or less, 7,5% to get 4 and 2,5% to get 5 at 2-1, and something like 50% to get 3 or less, 40% to get 4 and 10% to get 5 at 12-10. Just think the chances should be different. Beyonde that we can do something similar with the achievments rewards, doesn't need to be an item, could be a ticket for pvp, for infinity war, or w.e