Reduce work and hence let someone else work for him (increase employement)
This will only help if the rich person is working in a relatively unskilled labor intensive field.
Spend more money so he/she can keep up his/hers income (boost economy) - same as your fourth point
Keynesianism- what youre apparently basing this on- leads to illogical predictions during recessions, such as personal saving rates falling faster than investor savings until consumer goods shortages occur, and doesn't apply to real life.
Profit from social security, since increasing cash flow leads to (possibly) higher tax-income.
Cryptocurrencies are hard to tax. Indeed the whole point is to deny the kind of control that you're talking about to a government.
In conclusion, such a system would only be beneficial if you're trying to lower tax revenue.