Stupid is not an objective assessment though. I think Facebook is stupid, and I don't use it. I'm clearly in the minority, but that doesn't make me wrong, because there is no universal, objective standard on what is or is not "stupid."

I think the point is that stupid things can still be popular, and stupid ideas can make for successful businesses. Americans in particular tend to have a purely capitalist viewpoint that equates "profitable" with "good".

Hell, the "Pet Rock" sold millions, and I would hope we can all agree that was a stupid idea.

I think you are proving the point. Yes, I would agree that the pet rock was a stupid idea. Assuming I would find any reason to want a rock as a pet, why would I pay for one when I could simply go out to the garden and find one?

Yet many people did find the idea not only not stupid, but compelling enough to pay for.

So "stupid" is an entirely subjective assessment. I would never have invested in the "pet rock" idea as a funding venture, but clearly if I had done so at the right time, it could have been rewarding to do so.