Low taxes make it so the wealthy no longer have to invest in a robust economy. They can amass wealth and power by grabbing up all "the stuff" instead.
I'll wrap this all up in a bow for anyone who's interested. High tax rates result in economic growth because they FORCE the wealthy to invest in a productive economy. Low tax rates relieve the wealthy of this burden because the wealth thereby accumulated enables them to obtain a return OF investment, rather than a return ON investment.
All they have to do now is create periodic crises, like the mortgage meltdown of the last decade, then acquire boat loads of real estate (or other assets, like pensions) at fire sale prices. They don't want to earn a return on the assets made valuable by a strong economy; they want the assets themselves. They want all "the stuff" And now, with $2 trilllion in idle - i.e., hoarded - corporate cash, they can get it. They can buy your congressmen and senators, too.
The disparity in wealth and income we see today is not the desired end, but rather the means to the desired end. And that desired end is power concentrated in their own hands.
The economic pie is not finite. There's no limit to how large an economy can grow. But the power pie is finite. More power for one means less power for another, no matter how much total wealth and income there are in the world.
A larger economic pie benefits the middle class not only with better living standards, but also with things like functioning democracy through which they have a greater share of the power. More power in the hands of the unwealthy means less power for the wealthy.
And the wealthy hate this. So they PURPOSEFULLY shrink the economy in order to squeeze the middle class of its power and amass it for themselves.
THAT'S the end game. They desire a return to feudalism - I've recently even seen the term "neo-feudalism" in print - when the wealthy class had more power than at any other time in the common era.
And they're doing a brilliant job of driving us there.