Have I just spent my career cutting costs?

You are good at something real. You can get better terms than almost anyone in the room. And still, at night, you wonder if that skill has only ever served the ledger — never a person, never anything that would outlast the quarter. Notice what you are actually asking. Not "was my work good" — you know it was good, you have the numbers. You are asking whether good work, aimed only at a number, counts as a life. That is a fair question. It deserves a fair answer, not flattery and not despair. You cannot go back and redo the deals. You can look at what the savings bought — a project funded, a team kept employed, a company that didn't fold. If you never looked, look now. If there is nothing there, that is useful information too: it tells you what to aim the next negotiation at.