Most guys in NBA are moved all the time, except for “core” guys that basically only leave if they want to. The biggest superstars are considered to be obviously worth the max by every team, and even adjusting the rest of the team’s philosophy to keep him by every team.

Depends on the case, really, I don’t see that rule. Guys like Carmelo Anthony, he was just moved. He just became a guy that’s no longer core. There wasn’t anything else. It’s pretty common and understandable as you are over 30 and decline in form lol. For example Chris Paul, while still active and sometimes great at basketball, was not considered max material by Clippers, and basically was discarded by every team since, not his choice. This is the common way. More rarely, players are still valuable in their 30s but just unhappy, but that’s not a rule at all for sure.

Duncan, Kobe, Curry, Nowitzki are some of the biggest “superstars” of the last years and they never moved.