There does indeed come a point where taxation reaches high enough levels that people (and groups of them a la corporations) lose interest in exerting greater ef

There does indeed come a point where taxation reaches high enough levels that people (and groups of them a la corporations) lose interest in exerting greater effort. The popular actor Ronald Regan famously noted that he would have produced far more movies, but it just wasn't worth it under the confiscatory tax rates. Most of the time, people will indeed continue producing without such drastic obviousness - but there WILL be a tapering off of productivity, and history makes that clear to those willing to see the objective facts.