My point remains. People have free will and will take job offers for many various reasons.
Maybe after a few years in Philly he's sick of dealing with the cold. Maybe he likes the tax rate better in Arizona. Maybe he drove through the desert at sunset and was blown away by the sight (which if you have never had the opportunity, I recommend putting on your bucket list. Breathtaking.) Maybe there are some players here he doesn't get along with and would rather not be teammates with. Who knows. Maybe Buffalo had a competitive offer and he just wanted something different. We don't know and likely won't know.
Yes more times than not it comes down to cash. It's like that in most job offers. But there are other factors where if things are close matter more than others. Maybe at this point he wants guaranteed nicer weather over the possibility of winning another Super Bowl.