Pretty much, yes.
As rooster said, we were the only major industrialized nation that avoided being majorly bombed. That means we got to arm and help rebuild Europe, which meant we raked in the cash. But that was at the expense of the destruction of large portions of Europe, China, Japan, and Russia.
So FDR had nothing to do with it. Even if his polar opposite was in the hot seat at the time, we still would have come out ahead.
One of the unintented consequences was that, while we retained much of our industrial capacity while europe & Japan had to rebuild theirs (giving us an edge during this time) when europe & Japan had rebuilt, their steel and other related industries were more modern than ours. Thus, giving
them an advantage.
However, for a long time we still had plenty of capacity.
