Whats the goal post, is it that he is a 6th man on a real contender masquerading as a starter for us? Because thats a different argument than if he is worth a near max level extension.
You say Josh but what about Joe, what about Al Horford? All of those guys got theirs too and turned out that they were nothing more than role players on TRUE contenders. So why keep referencing Josh in the scenario? That entire era proved to be pretenders ultimately. So honestly, why pay anyone, ever, if that's the case?
This is business at the end of the day. Acquiring assets is only one part of the equation. You have to secure them or flip them. Or both. JC can net us something of value but we still need to secure him to do so.
His value is only being driven down by those who are trying poach him from us later. That's it. Everybody wants JC, even according to your guy. They all want us to fumble his negotiations so they can slide in. If we low ball him, somebody will pay him more. Watch.
JC is getting 20mil per AT WORST from somebody, no matter how you feel about it.