For example, here's Nihal Sarin beating Magnus at a blitz game at 16 years old: https://www.chess.com/events/2021-magnus-carlsen-vs-challeng.... Sarin is currently rated #5 on the chess.com blitz leaderboard with an absurd rating of over 3100. Online speed chess is just a different animal - ratings are different, everyone plays lots more games, and even Magnus loses fairly often. These players are all rated high enough to be competitive with Magnus at certain speed time controls, which is my point.

And here's another example, with FM Yoav Milikow beating him on stream in 8 moves at either 15 or 16 years old (depending on Yoav's birth month). Speed chess is a different animal. https://youtu.be/mor6qpyT7jA

Losing says nothing about the seriousness of the game