How many quarterbacks have "negotiated for every penny"?
Many of them - Brees, Rodgers, P. Manning, etc. They refused to sign until they were somehow the highest paid quarterback - be it average per year, total contract size, signing bonus or guaranteed money (Dak's case).
Now did that cause their teams to not win SBs? That's probably happened, just saying that did Brees, etc. not care about winning SB? Brees and Rodgers both had one ring, they know that that doesn't put them in the top echelon of NFL quarterbacks among many NFL followers, by itself doesn't get them in the HOF, either. Just ask Trent Dilfer, Doug Williams, et al. Heck Plunkett has two rings, and he's not in the HOF!
It's not an either/or thing, no guarantee that if Dak took $35 mil it'd mean a SB win. And someone mentioned that if he did, the Cowboys could have signed Wright. Would signing Wright made the defense top-10? No, too many needs on defense.
Don't know about everybody else, but when I negotiated my latest job pay, I asked for what I felt I was worth, it definitely caused a strain on the company's finances, but that doesn't mean I'm not working hard to make the company very successful. My taking lesser pay was also no guarantee of company success, like Dak I have little or no control over other facets of the company. If Jerry screws up the draft, or screws up free agent signings, then what good did it do Dak to take a few less million per year? Nothing. It's all supposition, the future isn't known.
I wish Dak had taken less, sure. But I can't see inside the man's head, maybe in his mind he feels taking more money will make Jerry watch free agency closer since he has less money. Maybe his agent sold him a line of bull and convinced him the $40 mil is no big deal.
Maybe Dak thinks a lot of things, we cannot know how committed he is to winning SBs....