...or so Hogarth Hughes tells the Iron Giant.
And it's that simple.
No one has to accept you just the way you are... And that includes yourself. If you do not like what you've become, you can choose to be better than you are.
There is nothing wrong with choosing to change who are. You are always who you are, even though you might no longer be who you were. That does not have to be a bad thing.
Be who you want to be.