Many cult members leave through the persuasion and persistence of concerned family members.
Many cult members have also left directly through intervention efforts.
They key issue is how much harm the group may do during whatever time a member remains under its influence.
Of course this varies from group to group.
In Ching Hai members appear to be financially exploited through contributions and labor provided.
FYI -- Rodney Stark has been criticized academically regarding his objectivity concerning groups called "cults."
Here is an excerpt:
Zablocki made another, potentially more damning charge, however–one that Robbins did not take up. A significant amount of cult money, he wrote, has gone to scholars–in support of research, publication, conference participation, and other services. Zablocki did not name names. But a number of professors freely admit that nontraditional religions (in most cases, the Unificationists and Scientologists) have cut them checks. The list includes some of the most prominent scholars in the discipline: Bromley, Barker, Rodney Stark of the University of Washington, Jeffrey Hadden of the University of Virginia, and James Richardson, a sociologist of religion at the University of Nevada at Reno. All five have attended cult-subsidized conferences, and Bromley, Hadden, and Richardson have occasionally testified in court on behalf of cults or offered their services as expert witnesses against brainwashing theory. "This is an issue," Zablocki wrote sternly, "of a whole different ethical magnitude from that of taking research funding from the Methodists to find out why the collection baskets are not coming back as heavy as they used to."