Your nescience is mind-blowing js!
FDR, by any honest assessment, prolonged the great depression by at least 7-years and probably more like 15.
Those "evil supply siders" you so love to disparage are the ones who are responsible of 90% of all R&D that has lifted the standard of living, not only in this nation, but around the world.
Leftist/statist ideology has historically led to wide-spread misery in it's socialism brands, and genocide in it's communist and fascist forms, throughout it's sordid history.
....Aaaaah, but i almost forgot: You leftist/statists like to create your own version of history as you need it to rationalize your failed ideology and it's dismal policies.