My great-grandfather left his shtetl in the Pale and came to America for three reasons.
1) to avoid the pogroms.
2) to avoid impressment and involuntary service in the Czar's army.
(I thought that was a hell of a thing. Either the cossacks come and try to kill you, or you could be forced into the military to serve involuntarily for twenty years. Or both!)
3) To get away from the Rabbi. He was sick of it. Sick of the stifling traditional life.