[ricardobeat]

Any tech savy person knows that has a strong possibility of being a password. Grab an ID, google "your name gmail", log in.

The kind of weak encrypting scheme you can remember is easily defeatable, this is still very vulnerable even if you leave one or two letters off (which you'll have to remember in addition to the scheme). So, going back to the parent, no, this isn't safer than a password in your head.

[petitmiam]

but this isn't the password for gmail. This is the password for the password manager account. So you need to know the password manager they are using and the username to match with the password. They have to find this out within the time that we've realised we have lost our wallet and are changing the password.

Obviously this is still less secure than no password in the wallet at all, but I don't think it's "very vulnerable" as you are claiming.