You can reject someone’s opinion and still organize your life around disproving it.

Dismissing an opinion and being ruled by it are entirely compatible. Someone told you what you would never amount to, and you have spent fifteen years assembling the counterevidence. The verdict was rejected and it is still setting your agenda, which is a more complete form of influence than agreement would have been.

Ask what you would be building if that person had never said it. If the honest answer is something different, then their remark is still in charge. You do not have to concede the point to stop letting it choose your direction.