A core tenet of sports and competition in general is that underdogs often overcome pre-established notions. It’s the reason why almost every culture in the world has a tale that mirrors David vs Goliath. It’s the reason why your parents most likely managed to get out of bed every morning to feed your dumb ass - because they believe they could overcome the odds - only for you to grow up an idiot and not understand that words have meaning.
NBA champions cannot by definition be “world champions” regardless of the talent variety and pool in the league. The NBA being the best domestic basketball competition also doesn’t translate into the US winning every international game or competition - as evidenced here.
It is the point of sports