[2021] Riot expect grandmasters to have 66%+ winrate to climb to challenger

So in grandmaster you win you gain +10LP but if you lose -20LP. Meaning to climb you need more than 66% winrate which is unrealistic and stupid if you are solo queue. Therefore, many people just sat at master 9XLP, and wait until next morning to spam games until they reach challenger. Why is Riot not fixing this and punish people for reaching grandmaster? I literally stopped playing after reaching 9X lp because there is no point.