More importantly, why don't adults give up names that clearly put them at an economic disadvantage? The same reason people don't sell houses when they are almost always a bad investment; pride, sunk-costs, sentimentalism or other reasons for their subjectivity.
https://www.reddit.com/r/namenerds/comments/10hssp8/why_do_p...
As an orphan that has wanted a last name change-- it's mostly because I am afraid of being locked out of my google account. Haven't I suffered enough?
Google has a surprising plethora of functioning, non-buggy tools for migrating an account's data to a different account. Do some research about what can't be migrated and make the change for everything else.