Liberal ideas have no history other than failure and you think we can't learn from it?
New Deal set the stage for a new society. FDR made it easier for workers to unionize, and started taxing the rich at confiscatory levels. It didn't hurt that first the war and later the baby boom put everyone back to work. The result, as you can see above, was the creation of the American middle class.
Between 1940 and 1970, the bottom 90 percent went from making, on average, $12,000 to $33,000. The top 1 percent, meanwhile, were stuck making "only" $300,000 this whole time. It's what economists call the "Great Compression," and it was a story about workers having the bargaining power to ask for higher wages and the rich not having much reason to ask for higher wages themselves. That's because top marginal tax rates were so high—at their peak, 94 percent—that it wasn't worth it for CEOs to pay themselves that much more. Besides, that was just something executives didn't
do back then. George Romney, for example,
turned down a $100,000 bonus in 1960—and those are unadjusted dollars—because he didn't think anyone needed to make that much more.
This chart explains everything you need to know about inequality - The Washington Post