Current pensioners didn't pay enough in. That's one of the reasons why we have such a large national debt.
Not all pensioners are rich. So lumping all pensions together as rich is a gross generalisation. But a considerable proportion of them are rich. Really rich.
The middle class pensioner group is one of the richest groups in society with large private pension wealth and benefits as well as significant housing wealth.
We need to implement progressive taxation that taxes the richest pensioners. Taxing the poorest is pointless because they have no money.
Personally I am in favour of increasing inheritance tax considerably to recover the money that went on the national debt instead of taxes. This would also flatten the wealth distribution more, as money flows to people who work for it rather than just those that inherit it.
Unfortunately any attempt to progressively tax rich pensioners more, be it through inheritance tax, property taxes, income tax or making them pay more for end of life care or reduce benefits like the triple lock or WFA are usually met with howls of protest.
We really need a leader that is going to step up to the plate and increase the taxation on the richest in society, while putting forward the message that it is the richest that are going to bear the burden and not the poorest of that demographic.