The reason why an ageing society needs some degree of austerity is quite obvious. Most countries run some sort of public pension scheme and offer medical and other sorts of aid to the elderly. As more people consume those services and less workers pay the taxes that fund them, austerity is needed.
Except that we don't have a problem paying for it. So how do we justify screwing people out of what they worked for all their lives?
Not to mention, if we do screw the people out of it, the economy as a whole is going to take a serious hit.
US politics were not alone in shifting to the right since the 60's. And the influence of "the rich" as in ordinary rich individuals was not the determining factor. The development model of the post-war era exhausted itself and the leading economists and academics of the world suggested several policies to remedy the situation, and those were usually a push to the right (in some issues anyway).
That's not actually what happened in the US. In the US it was all about an organized effort to change the distribution of wealth in the nation. The rich wanted more. So they fought for the politics to give them more.
At least I'm offering a theory!
Offering a theory that is entirely inconstant with the real world is worse than useless. Why don't you look for a theory that is consistent with the facts?
I pointed out that the US of the pre-crisis years was consistently saving too little, and that the investment rate has been falling. So it makes sense to follow policies that reward investment at the expense of present consumption. What is your theory, given that it is a fact that consumer spending was high?
Finally, some quotes:
Savings started to collapse in the US with Reaganomics. That was contrary to the theories in vogue at the time. Rational Expectations said the opposite would happen. Supply Side economics said the opposite would happen.
So what is the theory of why savings declined? It's really very simple: People started spending as if their incomes were continuing to rise even though their incomes had ceased to rise. They did that by drawing down their savings and then going into debt. This is normal behavior. People are unwilling to live as if they are falling ever further behind others when they are working harder than ever before. Also, the private pension system has been looted and destroyed. And people just do not put away in private savings what pension plans used to put away for them.
However that only explains the low savings rate. It is irrelevant to the investment rate. Irrelevant, in that it means nothing in any way, shape, or form. We are drowning in capital. There is no such thing in the US as a business that cannot invest because there is not enough investment capital available in the nation, or that the costs of capital are too high.
So the lack of capital is not a problem. The lack of savings is a problem, but not a problem for business investment. It in no sense explains the lack of business investment. What explains the lack of investment is Wall St directing money out of the country instead of investing here. What explains lack of investment is the lack of consumer demand due to the fact that wages are far too low.
The ultimate foundation of all of America's economic problems is that labor is extremely underpaid. The United States economy does not have a problem that does not have as a foundation the fact that labor is underpaid by at least 1/3.
And because labor is so extremely underpaid, because companies are not investing, because Wall St has become rabidly anti-investment, because government no longer has the money to invest, that is why we have the budget problems.
Now austerity is an attempt at "solving" the problem by deliberately making the problem worse. The economy requires the opposite of austerity. The only thing austerity could conceivably accomplish is a smaller national economy. That's the only thing that it has ever accomplished.