So visiting a website is doing a stupid thing? Your recommendation is essentially telling people to stop visiting websites or accept bad things will happen to them. This is not a healthy viewpoint for growing the web.
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.