Not the point. I am opposed to any taxes imposed after the event. If a chancellor wants to make a tax change going forward then fine. People can plan and adjust and do whatever they want to in the light of what's coming. You cannot change what's already happened, so it is unfair to tax someone on what happened previously, like accumulating your wealth.
Suppose family A and family B earn the same and have the same number of kids, houses, costs etc. Family A decides to save as hard as they can, spend little and after 20 years have amassed a modest pot of savings. Family B does the opposite - spends everything they earn, goes on posh holidays, eat out all the time etc and after 20 years have nothing.
Would you say it is fair to then take 2% of what family A has off them, and give it family B? I would hope you would not.
So having agreed the principle, the financial cut off becomes irrelevant. It may be financially and practically expedient for the chancellor, but it is morally wrong.
What if family A decided to risk everything on a business venture and as a result of their entrepreneurship, working all hours and countless sacrifices, they are now worth £10m? Had they been told 20 years earlier, "Beware, if you are successful, the state will take x% off you", they may have decided to not risk everything.
Apart from anything else, we already have a high rate of wealth tax, called IHT which takes 40% of rich peoples' estate off them every 30 years or so.