The stupid behaviors listed above are putting your google password or payment info into a random blog, or running a program it gives you because it says you need to update.
Doing that is stupid whether it's http or valid https or broken https.
Okay, but if a user went to a http version of YouTube and put in your payment info to buy a movie, as opposed to remembering it should take him to an https Google page, I would find that a plausible situation that is hard to blame the user for. Attackers being able to hijack the reputation of sites is problematic.
Youtube does not have 0 reputation. The point of this thread is arguing the merits of requiring sites that don't handle sensitive informationfto use https.
Doing that is stupid whether it's http or valid https or broken https.