[zibby8]

The issue isn't his belief. It's that he's throwing a tantrum and has ruined two Chess tournaments (so far). He's free to believe whatever he likes, but to resign in a match in a tournament is not fair to all the other players.

[Retric]

It’s hard to see how other players are negatively impacted. If anything the publicity is likely a net positive for them.

[zibby8]

The top 8 players in the tournament get invited to the next tournament. Hans Niemann got a free point from the game Carlsen resigned. That impacts the standings for all the other players. It’s hard to see how they’re not impacted.

[Retric]

That ultimately impacts one player if Hans gets in instead of them, or zero players if it doesn’t change the results.

[zibby8]

Talk about moving goal posts

[Retric]

“all the other players” vs 0 or 1 other players.

[zibby8]

In addition to that one, very concrete impact, the situation may also have subtle effects. Players may be going into matches against Hans being down a point when they would have been tied, changing the psychology of their play style. Similarly, Hans may play more confidently being up a point. Even spending a single second thinking about the situation is an unnecessary impact forced on the other players by Magnus. Pretty unsportsmanlike.