I've actually not signed up for services at all because the couple username variants I tried were already registered.
I was also recently annoyed at being forced to switch to a new system for my credit card, and it's a unified system with all their other cards and banking customers, and still uses "username" (instead of email) as a login, so of course my name was taken. I decided to just append some random characters, and then realized I could just generate my entire username and have been doing that since, when I don't care about identifying myself to others. My password manger saves it, so it really doesn't matter to me.
I was also recently annoyed at being forced to switch to a new system for my credit card, and it's a unified system with all their other cards and banking customers, and still uses "username" (instead of email) as a login, so of course my name was taken. I decided to just append some random characters, and then realized I could just generate my entire username and have been doing that since, when I don't care about identifying myself to others. My password manger saves it, so it really doesn't matter to me.