Assessments of the Business Plot tend to fall into one of three categories:
- Smedley Butler was telling the truth: there was a serious conspiracy, made of conservative politicians and business leaders who had the brilliant idea of recruiting a self-described socialist as their military front-man.
- Some rich idiots were shooting the bull at a cocktail party. Butler heard about it and overreacted/exaggerated.
- Butler made it up out of whole cloth for personal gain or in order to slander/discredit the accused plotters and their end of the political spectrum.
When this has gotten discussed in the past, opinions seem to lean heavily towards option #2, with a few vocal partisans for #1 and #3. I personally consider #2 and #3 plausible, but #1 very unlikely.
If #1 were indeed the case, then the plot might have gotten further had the plotters picked a different military front-man (MacArthur is the most frequently discussed candidate), but it was almost certainly doomed to failure in the long run: FDR was too popular, US political culture too hostile to the idea of a military coup, and the professional military too weak to hold the country down by force of arms.