You reached M+20 becoz it’s boring? I wont reach my M+15 if it’s boring.
You just played too much. I got my Greater Rift 70 in Diablo 3 before I stepped in back to do M+15 on me… previously all M+14s. I realized that there are other games to excite me. Shadowlands is in the works. But before that, I am ok with once a week 5-Mask, one Heroic Nzoth kill and one M+15 completion while I play other games.