Yes, that's true too, and I agree that taxation should be used to correct that sort of thing, but those with estates worth over a million pounds refuse to accept that this is a lot of money, regardless of the difference between what they paid for their house and how much it is worth now. It may be the case that a house value is only average for the street and that it was paid for from earned income, but that doesn't mean that the profit it has made was earned - it wasn't.
The current system takes more (proportionately) from the have-nots than the haves. Things like the amount at which people have to pay for care is static across the country, when the average house value is anything but. Caps on the amount that people should pay are often discussed, and again - a static cap could wipe out a family in one area and barely touch the sides of the inheritance for another.
The fact that people in some parts of the country have geographical mobility and others don't is very unfair, too. It prevents equality of opportunity and flies in the face of meritocracy.
I see all of those things as contributing to the drift to the far right we are seeing - people are disenchanted and resentful, and in many ways I don't blame them.
I know that those with (my definition of) wealth can 'earn' from it, and those 'earnings' are what I would like to see taxed. I understand people wanting to shield savings from inflation, particularly when they are retired and on a fixed income, but even modest savings are taxed if they are not shielded by ISAs, so it can be difficult for many people to feel financially secure, even after a lifetime of work. A lump sum such as an inheritance can make a huge difference to someone's life chances, and I do understand parents wanting to give their children those chances, but a cap on individual inheritance would be a lot fairer.
I don't see the point in an insistence on a figure for 'what is wealthy', unless we want to cap earnings - it is purely subjective otherwise.