FDR's policies were so unpredictable, varied, and constantly changing, that no one could no what investment was "safe" so no one invested much.
Truman tried to reinstate the New Deal, using the Korean War as the excuse to nationalize the economy via wage & price controls, railroad takeover, commodities, industry, etc. Same Wilson/FDR crap.
The difference? Republican Congress put a stop to it. Same thing w/ Obama — could have been far, far worse (even with Panzie Ryan)