I'll go against the grain here and say I don't entirely agree with what you're saying...
Sure, owning up and saying you had a HT surely shows you're confident enough to admit it / to 'own' it and don't mind all the questions. But that doesn't mean that you are NOT insecure about your looks simply because you admitted to getting work done....on the contrary, it shows that you absolutely WERE insecure about your looks....and hence had a HT.
Secondly, IMO, there is a very valid reason to keeping your HT a secret (if possible). One reason that i would choose to (try to) keep it a secret, if i get work done in the future, is because I simply get tired of people looking up at the high hairline when talking to me. It's a sh*tty feeling.
And to have friends and family know that I had a HT, I am pretty sure that they'd always be asking questions and that their eyes would occasionally be glancing up there, not out of disrespect of course - most likely out of curiosity - but would it would still annoy the hell out of me.
Don't get me wrong, I am not knocking people who are out in the open about getting work done, but i don't think it is right to imply that is always the best way to go about it.
Everyone is different.