This is the answer to most of the problems in most 1st world countries
A lot, but not this one. The rich are simply not rich enough to offset the demographic issues we have. In the last decades life expectancy rose months per year and even in America billionaires "only" own some 13k per person. With that you could offset ageing population and life expectancy changes for, two years maybe? It would be little more than a drop in the bucket.