I disagree.
"Protocol 1, Article 1 protects your right to enjoy your property peacefully
Property can include things like land, houses, objects you own, shares, licences, leases, patents, money, pensions and certain types of welfare benefits. A public authority cannot take away your property, or place restrictions on its use, without very good reason."
Taking money off people "because we can" would surely be challenged as not being a very good reason. Furthermore,
"There are some situations in which public authorities can take things you own or restrict the way you use them. This is only possible where the authority can show that its action is lawful and necessary for the public interest. If your property is taken away, you should be entitled to compensation."
So the government takes £200,000 off Mr Smith, who is then entitled to £200,000 in compensation. How would that work???
There's much debate in the US about the legality of wealth taxes and whether they would violate their constitution. I think we could expect similar argument here.