I think your statement is flawed. I don't think most basketball fans think NCAA basketball is "better" than Euro league ball. But it is absolutely more relevant. NCAA basketball games are on when people are awake in the US. A lot of people in the US went to a college that had solid basketball programs. A lot of people in the United States have done a bracket and paid attention to March Madness. The overwhelming majority of NBA players played in the NCAA, and the overwhelming majority of NBA players did not play in Euro league.
I don't think minor league baseball is better than NPB or KBO. But a lot of baseball fans have been to way more minor league baseball games (and seen some of those players go onto the big leagues) and are a little bit familiar with their team's minor league affiliates. They're not watching Korean and Japanese baseball at odd hours that isn't on TV.
I agree 100% with this mindset but unfortunately that is never going to be the case with r/nba. The majority of this sub cares way more about celebrity gossip/drama than they do about the sport itself. They'd rather hear about Lebron's instagram posts or Kyrie's third eye than learn anything about the game of basketball. Most NBA fans (especially on r/NBA) prioritize first and foremost their weird parasocial relationships with these tall millionaires.