Why isn't there more money spent on slowing ageing directly?

Removing senescent cells in humans could extend lifespan by 35% most of that healthy life span if we respond as well as mice did.
Longer healthy lifespans would make the economy more efficient mean more money for welfare programs, services, research and infrastructure as the same amount pp would be spent on schooling but since they live longer it would be a smaller amount of their tax bill later on. Unemployment would also drop as it's always been the younger generation 18 - late 20s with the highest unemployment or underemployment and the lowest wages.
On top of that a 35% extension in lifespan could let you get more than 35% as much done over your lifetime as the initial period of education would be proportionately smaller ie more working doctors nurses and engineers also increasing what pepole will pay in relative terms for manual work as more pepole have professional options.
Why isn't there more money spent on slowing ageing directly?
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