Being a declining contract doesn't provide justification for an overpay. And yes, right now it's looking like an overpay. He'll be making more next year than DJM, JJJ, Jalen Brunson, and Mikal Bridges, for example. There is still time for his contract to prove a bargain, but so far this season it's looking iffy... unless you also think someone like Jordan Poole's contract is a steal.
A team has to pay players. It doesn't have to overpay ty ones. That's how teams end up with things like... I don't know, a .192 winning percentage.
And no, a contract like Collins isn't exactly what you want if you want to acquire a star. There is no requirement that you have overpaid, undersized backup centers who can't shoot or defend include in trades for stars. Exactly zero teams have ever looked at what Zach Collins has currently is and said "yeah, that's the perfect piece that makes this entire deal make sense". Looking back at the last few big trades... nope, none of them included a ty overpaid Zach Collins-like negative asset. Maybe Bertans being passed around like a used up French to facilitate blockbuster moves for Gordon Hayward cons utes acquiring a star.
You're right, this ain't difficult, which makes it all that more impressive that you continually vomit all of this nonsense all over yourself.