Because everyone's retirement depends on the stock market. If you're unlucky and your portfolio vests the day after a massive crash, that can have a very meaningful impact on the rest of your life.

Maybe that will make everyone to think what is going on with this retirement plan build on stock market growth and expectation there will be something to buy with that "wealth" in future...

If it’s a bubble, it has to pop sooner or later. It’s better if it pops now before growing even larger.