Being a millionaire isn't enough for most people to retire these days unless you are older or relatively close to death.
But of course, $2M would be better, provide more buffer against the uncertainty and allow you to retire even in the US.
If you want to retire in the land with million dollar houses, well duh you gonna need more than $1M, and I'm sure plenty of people would love to have that. But it's not really a necessity. There's plenty of affordable locations for retirement on $1M budget.