The currency is never the only asset or unit of trade in an economy. As long as value and wealth were being created somewhere, inflation can exist.

Gold is interesting because more of it was being mined and produced all the time. There wasn’t even a finite amount of gold.

Thinking that a gold standard means no inflation (or in practical terms, deflation as the population grows) is a modern fantasy.

In addition to the security issues, they would have to deal with non-negligible transaction costs every time they wanted to convert it to actual money so that they could purchase something. If they were using it as an investment, they had to deal with the opportunity cost of underperforming $SPY.

Still, they have to worry about them and their family not being kidnapped.

Oh but hey, checkmate, burglar who is threatening to cut my daughter’s finger, my wallet is multisig !

It really comes down to the burglar's expectations. If most crypto holders used geographically separated multi-sig, these attacks wouldn't be worth the effort anymore.

It’s the same logic as iPhones bricking themselves after being stolen. Even if your specific phone isn't an iPhone, the fact that most phones are now useless to thieves discourages the crime across the board.