A lot of things happened that made the west wealthy in comparison with the rest of the world. Plague also didn't just happen once, it was a continuous thing with a few large events.

The reduction in population of some of those epidemics made fairly large improvements in the survivors' lives and can be seen as the stimulus in a lot of the progression of Europe.

Progress that led to wealth in the west wan't just the industrial revolution(s), it started long before and was the effect of several technological and social developments.