The hobby is an interesting place to navigate, many post across forums of experienced collectors and people with relatively no hobby experience question why what sells for what. Why does an unproven rookie sell for more than a proven hall of fame player or current max contract star? The answer is fairly complex and no answer can be given in short format.
However in basketball there is a ring culture unlike any other sport, the NFL nor MLB has such an emphasis on rings. League MVP's and players dominant for over a decade like Charles Barkley are looked down upon for not having a team accomplishment.
Giannis one ring has become relatively irrelevant amongst discourse with the narrative turning on him. Kawhi and Durant two rings have them in a similar place, instead of viewing their 2 Finals MVP's as all-time greats.
The three stars markets are in a seemingly downward trend regardless of what transpires during the regular season. Kawhi has played in all but 4 games and is on pace for an MVP finalist season, yet he is going down in price. Same with Giannis who is currently the #3 seed and #3 in the NBA.com mvp ladder.