Effectively, you increase risk (buy risk assets) but dramatically REDUCE your risk. Its "risk free risk taking"
And its this dramatical reduction in risk that makes the decision to sell those investments require a MUCH bigger overvaluation level in order to make sense to sell. You cant look at something that is 20% above its fair value and say 'its time to sell, its overvalued', when you factor in those risk dynamics, you will need a LOT more than simple overvaluation. You got to factor in that your risks will increase when you sell then and your natural shorts increase.
When I see rich, smart folks saying 'I just sold all my stocks, this will end badly' 'sell your house, this is a bubble' 'its not time to buy a home, rent, its a bubble', I dont get it. I dont think it makes sense to do that most of the time. I think they are just being sloppy and not thinking things through