Ideally you'd spend the taxes on things that help people, but I would argue that even simply destroying the taxed wealth would be an improvement over what we have now, if only in that it would counter wealth/power disparity and enable democracy to work better. Allowing a subset of the population to accumulate power divorces their interests from the majority and represents the biggest threat to modern society.

It would be a huge waste though. We should probably spend it on food, education, and healthcare instead.