I think people are motivated by many things, often combinations of things, and with the cult, the basic motivation for most of the premies I knew, was a sincere desire to know truth and love, to have an experience of God, and to be happy.  Period.  That was what got people involved in the first place.

Then, once in the cult, it got, well, complicated, for many people, mostly because neither knowledge nor Maharaji actually delivered, and there were all these excuses as to why that didn't happen, mostly because it was the "student's" fault for not being devoted enough, not having enough faith, being confused, being too much in your mind, blahblahblah.

So, when the catch 22 happened, some people dropped out, but some people got ambitious or wanted the things that would finally give them what they wanted.  So, they wanted to be "with" Maharaji or his family, or they wanted some power position in the cult, or to be "noticed" by Maharaji, or to be admired by the premies as high, or spiritual, or a cool, inner-circle premie, or to be an initiator (these were some of the MOST miserable premies I ever knew).  

 At one point, being a rich premie was a big deal, partly because Rawat's insatiable need for money meant that such people got attention from him so they would give him money, and so people had the resources to travel around the world to see him.

And so the motivations changed over time.  They had to if you were going to stay in the cult.  You had to adapt.

So, with Marylon, I assume it started out pretty sincere, and changed, perhaps her kids became the most important, or perhaps she was psychologically abused.  According to Mishler and Dettmers, Rawat used to yell at and verbally abuse Marolyn for long periods and she sort of just took it, with her Catholic guilt.  That's just plain abuse, and I'm sure she didn't have much confidence to stand up for herself.  Perhaps accepting or overlooking Rawat's sex with premies and his mistress, was just the next step.