Market fall of 80% in a portfolio that has been diversified isn't that bad. Say you 50% in shares. It has lost 80% of that 50%. That's not so bad. You still have a chunk of savings.

If goverment bonds loose all their value, it means goverments are close to failing.

If real estate is loosing all its value. It means people have no money to buy houses

If all 3 is going on the same time, some serious stuff is going and I'm not sure your goverment backed account is really that secure.