I have seen various cultic entities, pyramid schemes especially, in which they lack an overt charismatic leadership or perhaps their leadership does not exist in such a public view. I've also seen some subpar cults who have cultic devotion but their leaders don't necessarily scream "Charismatic". Any thoughts about this?

IMO all that is necessary for a cult is a totalistic vision or belief of sorts, a fanatic conviction in adherents towards this vision or belief, and an 'Us vs Them' dynamic where the 'Us' consists of in-group members, 'Them' consists of anyone not in the group.

Thus, while a charismatic leader facilitates the creation and contagion of the vision, it is not always necessary.