Half a million is easy to pass though if you’re including property, that’s my issue. Make it £5M+ and I’d consider it vaguely sensible.
That being said, if it’s been earned legitimately (ie not via crime) then tax has been paid at source, so why should it have to be paid again? We already have inheritance tax which is bad enough, this would be an absolute urine-stealer. Let’s say I work hard and make a company that employs thousands, creates huge amounts of wealth for the country, and am able to set my kids up for life, why should I be punished? If people are following the rules on tax and avoiding it legally, then change the rules on tax in the first place. Don’t move the goalposts because the state is too inept to create something that’s not possible to bend.