Mortgages don't typically run for 50 years. There is a time cost to money. You are essentially advocating a partial 'timing the market' strategy.
Just lol at your blunt response to the original question then.
We aren't robots and what we know or believe to be the best course of action isn't always the one we take for various reasons.
If everyone did what they know if the best thing, no one would be in loads of debt, no one would be buying cars they can't afford and we would be far healthier as we wouldn't have an obesity issue. That doesn't make the objective truth any less correct...