Put yourself in the player's shoes. You visit 4-5 teams as a free agent, you get 2 offers. One for 4 years from the Bills, $10 signing bonus with a total package of $25 million. Second offer is for 5 years, $15 signing bonus, $32 million total package. Higher offer is from a good team. You meet the people, you like them, you like where they are headed. You go back to the Bills and they don't want to match the better offer. What would you do?
I would pack my bags unless the situation in Buffalo compelled me to stay for other reasons. If the Bills were on the verge of a championship, maybe. Maybe not.
$5 million goes a long way over the course of a lifetime.