Political-philosophy wise, the MEK has tried tp make some Iranian version of a fusion of Shia Muslim fundamentalism and Marxism, while also pledging to, if given the chance, practice their goals democratically. Like many others on the Left they were in favor of opposing the Shah, but also like many others on the Left and many truly moderate democratic forces, they never succeeded beyond just being part of the broad - Khomieni controlled - coalition that kicked out the Shah. Then they were kept out of political participation by Khomeini et al.
Maybe Iranians are smart and see the pretense by the MEK of now being “democratic” yet also being Marxist and also good fundamentalist Shia. The contradictions are likely just too much for most people to believe that one or more of those contradictions will, when desired, be sacrificed by the MEK for what is their true priorty (which I believe is heavily Marxist).
It’s a cult as the dictionary defines one, with a woman leader who requires her female followers to wear head scarves, separates families, requires celibacy, punishes those who don’t obey rules, requires street corner solicitation for funds, among other things.