It’s often used for pledging the mortgage.
https://www.credit-suisse.com/ch/en/...ng-201905.html

Personally, I wouldn’t wanna touch my 2nd Pillar as “you never know” however 3a can be always systematically accumulated back with a bit of discipline in terms of saving.

All your investments accumulated in the pillars 3a will not be taken into account for the wealth tax. With current online offer, for a 97% investment in etf, you could accumulated more than 300kchf over the next 30 years. It could be at least another 1000chf wealth tax you won't need to pay.