They thought wrong.
It is a pretty good analogy.
The Left, in general, has a huge problem with reality. They believe "good intentions" are far more important than "good results". In their assumptions about reality, "good intentions" by the "right people" always results in "good results".
History has proved them wrong many times. They simply say there were not enough "good intentions" or the "wrong people" were in charge.
"The road to Hell is paved with good intentions."