Your confusing your economic and social theories. Trickle-down economics / reagnomics is not the same as Keynesian economics. Keynesian economics has been the unofficial U.S. policy since the 1930s/Great Depression, well before Reagan was president. It's what prompted the New Deal. Essentially, the way to get out of a recession, is to spend money, namely on government jobs programs. This will enable individuals to spend money. Those individuals need to spend money so businesses can earn money so they can buy materials, and pay their employees and those employees can spend money, etc. Buying materials produces more jobs, and it keeps rolling. The theory only works if people continue to spend instead of save. Which is why there's that pressure to spend. Problem is, the theory also assumes that at some point there is some sort of production that's going on. Unfortunately most our production is overseas now so those that really benefit from Keynesian economics are other countries.
Trickle down economics sounds similar but the basic idea was that if those who earn more can get more of their earnings, they'll either invest in businesses (thus giving them money so they can buy materials, pay employees, etc.) or buy really expensive things. Problem with economics is every step of the way those that benefit save a little off for themselves, thus by the time it reaches the lowest economic rung it's mostly depleted.