I think the challenge points should be a closed circle point system and not a way of getting even more coins.
Add a shop with not many, but gppd items that players will actually use, like a katana x damage sword (but not katana x itself) for an absurd number of points
If you want, you can also just straight up place the legendary items in there so players eho qq about not getting the items can just buy rhem there after spending a lot of time completing challenges.
