I optimize everyone else's systems — did I ever build my own?

You have spent years making other people's systems run better — the pipeline, the pricing engine, the onboarding flow, the dashboard that made someone else's quarter look good. You did it well. That is not in question. The question you are actually asking is whether skill spent on someone else's machine counts as yours. It does not, and it was never going to. That was the arrangement the day you joined the team and cashed the paycheck. No amount of elegance in the work changes whose name is on it. What is yours is the judgment you built doing it: knowing what breaks under load, which constraint actually matters, what to cut without asking. That judgment is portable — you carry it out the door every evening. The only question left worth asking is what you and the people beside you choose to point it at now.