An issue with this is that even if pensioners are millionaires and getting state pension, they’re definitely the right people to trickle it down to where it’s most needed.

I think “30% of pensioners are millionaires” is also a bit moot given the majority of those are living in properties that they didn’t buy for millions and have lived in while house prices have gone up. My parents for example are probably close to your millionaire threshold and it seems unfair that they’d have to sell their home they’ve lived in for decades and want to continue living in just because the housing market has pushed its value past the point where it seems like it should be taxed. They’d have to sell it just to pay that tax and move somewhere smaller, which seems unfair to force on people approaching 80yo.