The Laffer curve is based on a very real phenomenon.\
Except that it wasn't because there has never been a time in this country when taxes were so high that they harmed economic growth. Laffer just assumes that high taxes harm growth because of his prejudices, yet we had high taxes in the 1950's and before Clinton raised taxes in the 90's, that was the longest period of economic expansion in the modern history of the US...with a top tax rate of 90%.
We do have a history of low taxation harming economic growth, and that history is very recent to this century...first, the Bush Tax Cuts and then the 2018 Russia Tax Cut. Both tax cuts prompted economic collapses. Bush the Dumber even tied his tax cuts to the housing market in 2004...the same housing market that would collapse 2-3 years later.
But the reality is that borrowing is always based on a belief that it can and will be repaid at a later date either through tax revenues or through more borrowing. Ultimately there can come a time when lenders no longer believe that revenues can keep pace with borrowing and money becomes too expensive to borrow. At that point there are other mechanisms that can be used but without a faith in government and its eventual ability to pay its lenders on time the final result could end up being economic collapse caused by collapse of the monetary system.
Except that time will never come...if borrowing rates would be affected, we would have seen it by now. But here we are, 10 years removed from the last Financial collapse, and borrowing rates continue to be at or near-zero for the government. What that says to me is that now is the time for the government to borrow to fund large spending programs that get people employed, educated, and get them health care. What's been proven is that kind of stimulus helps stave off recessions because the government is making up for the drop in consumer/private spending.
When you cut government spending, but don't replace it in the economy with other spending, you contract the economy because the only way an economy grows is by spending. That's why targeted stimulus to those at the bottom of the income range are always the best stimulus; poor people spend more than rich people.
Saving doesn't grow an economy...it contracts it.