If you actually listened to him talk, then you'd know that he was really hoping to stay in Oakland, or even sign an extension. And he said that in interviews after he signed with Toronto when he really didn't need to. He's not just after the most money. Comfortability is clearly important to him. These things are a case-by-case basis, even if the vast majority of times it does come down to money.
With Semien, he really seems to like being in Toronto, we can offer him a good amount of money, and we're going to be competitive for a while. It's as great of a free agent destination as anyone can ask for.