Thinking something is over or under valued is very different from general confidence in the economy. In daily life you're not betting on the economy, you're part of it. You work and spend even if you think the nukes are going to kill everyone. Confidence has a vastly weaker connection to demand for goods.
If people think the dollar is significantly overvalued, they'll switch to gold, bitcoin, rolls of toilet paper, or other forms of ad-hoc currency. That's what happens in countries with 1000% inflation, for example.
