Ronald Reagan left office in January of 1989, for the mathematically challenged that was 20 years ago. At the time the US economy was doing very well. This was in stark contrast to how the economy was doing in Jan 1, 1981, which was pretty crappy.
And for years after Reagan left office, the legacy of lower taxes fed American prosperity. Private investment spurred by those lower taxes led to technological innovations and rising wages.
However along the way political leaders of both parties came to like currency manipulation as we never have before. The result was a series of bubbles that eventually burst in a pretty bad way.
To blame Reagan for the irresponsibility of the politicians including and especially the current and former Federal Reserve chairmen, is to completely misunderstand the linear nature of time.
Without that understanding of the linear nature of time it is virtually impossible for someone to understand cause and effect.