Unpopular opinion: you met your potential
So many posts, here and otherwise, are people lamenting that they didn't meet their potential, or what they felt the world expected of them as a "gifted kid".
This can either come as a jab or a relief, but chances are you reached your potential whether you like it or not.
What I have seen anecdotally is that children - mostly in the US - are identified for gifted programs, assume the gifted label, have an average life, and mourn what could/should have been.
Most of the time, schools and districts had established programs that drew extra funding. Teachers selected kids that seemed to behave or do well, or who they wanted out of their class, to go into the programs. There may have been an aptitude test, but most were based on observation and nomination.
This has very little to do with giftedness. You were probably misidentified for nefarious purposes then lived up to your actual potential. If you're carrying around guilt or remorse for a life not lived, you shouldn't. You're the only one putting that burden on your shoulders.
Actually gifted people know there is no 'formerly gifted', and there is no 'I was gifted as a child'. There's also no shame in being average, and it's not your fault that you were mislabelled. Let go of the chip on your shoulder and you'll see how much it was weighing unnecessarily on your self worth.