It's not as simple as 'multisig', but let's assume multisig gives you immunity somehow.

A proper Multisig setup certainly makes you much harder to attack than a person who relies on one vendor (but increases the complexity of your setup).

If I had to take a guess, probably 99% of users are not going to multisig.

Bitcoin's defense can't be "let's hope users pick hard mode", otherwise, the Bitcoin revolution will amount to "have fun playing with your Bitcoins" as Trump said.

Unless we get Bitcoin's non-custodial UX close to using a debit card, this will be mostly about trying to mine some fiat and posting memes.