Gil sellers top the achievement list!!

[Conradus]

It's not against ToS to share accounts, is it?

I believe it is, actually. In FFXI it definitely was, except when a parent or guardian shared an account with a minor under their care (you couldn't have your own account if you were under 18 in FFXI, but players could be as young as 13 by sharing an account with a parent/guardian).

Addition:

Yep, it's still against the rules to share your account, except with a minor under your charge. Cut and pasted from the User Agreement:

3.1 Sharing Account Information. You may not share your account or login information (such as your Square Enix ID and password) with anyone except your legal guardian, your minor child, or SQUARE ENIX. You are responsible for maintaining the confidentiality of your account and login information, even from your friends and family. If you violate this provision, you may unexpectedly lose access to your account to a third party without recourse against SQUARE ENIX. SQUARE ENIX will not be obliged to credit your SQUARE ENIX Account with Crysta or other points or awards, which may have been used by a third party as a result of the violation of this clause.