I‘m also holding individual stocks.
That said, I‘d be less concerned about ETF issuers.
Countries may fail because of politics. Broker may fail because of bad risk management, IT security etc. Even fraud, maybe.
An ETF though? Seems pretty straightforward and not too many vectors for fraud - and I doubt I can be wiped out in a singular event, such as someone hacking my account/credentials.
I haven’t really been in a situation where I was about to invest (close to) 100% of my liquid net worth into a single security. Most of my brokerage accounts don’t have access to U.S. ETFs anyway.
As for countries, I‘m not sure if I have (partly) reversed my opinion on this over the last year or so. But it’s just hard if not impossible to ignore (underweight) the U.S. at this point. While the U.S. got rid of their Trump (for the time being), Europe got new problems with the Ukraine war and cutting itself off from cheap Russian energy. But as far as alternate universes go, there are some in which Trump didn’t peacefully hand over power after the election and Putin may have decided not go all out on Ukraine. And the junctions between them are just a handful key decisions taken (possibly only on a whim) by these two world leaders.