Your premise is flawed. By what measure do you say “so many go back”? Meaning, how many exactly do you know who have left and then had disasters and then went back?
Its a perception thing. You see one or two and assume its “a lot” or feel, because its the total of you observation, that it must apply across the board.
its easy to understand that some who leave were df’d and they may have emotional problems to start with, hell id be willing to say a lot of those problems were brought on by life in the cult anyway.
That portion of “those who leave” may well have their lives fall apart, the cult was their support system in an already troubled life.
How many leave due to principled stand and do great? I know more than a few, myself included. Ive made new friends apart from the cult and expanded my life immensely.
I think your looking a specific subset, those who are forced out and may have emotional problems anyway, and applying that result to all. Your data is incomplete.