So meaningful-thanks for sharing!
The ones who left were the ones who had somewhere to go. From 1922 on, entrance to the US was cut off for most European Jews. Emigration to Palestine was limited by the opening and closing of the Aliyah safety valves, but the period of full, unrestricted Aliyah was only there for 8 or nine yearsl, and the orthodox in Europe were often discouraged by their leaders for various reasons, both religious and political.
To leave Eastern Europe in the interwar period took a combination of will, luck, and real -determination – a combination that was pretty limited