Tax Cuts Make People Work Harder?

A quick note on something I enountered while reading Do Tax Cuts Lead to Economic Growth? –

Longer term, people will presumably work harder if they keep more of the next dollar they earn.

This is right-wing conventional wisdom. It has been repeated and repeated until people … just repeat it. It is the Ayn Rand argument that people will “go Gault” if that have to pay taxes, and just stop working.
Who don’t people think that people will “work harder” if taxes are raised, because they have to make up what was taxed?
In other words, this kind of argument is just making stuff up because you have to have something to say. Either one works — if you want taxes cut say people will “work harder’ because they earn more.
One more thing: in what kind of world is “making people work harder” a societal good? Maybe in Ayn Rand’s world.
Shouldn’t our economy be about enabling people to have fuller lives, enabling people to have more leisure time, enabling people to spend more time with their kids, or reading and hiking and throwing frisbees with dogs?