The last straw for me was when I realised the Knowledge had not worked for me in over 30 years of sincere and constant practice. I could only see three possible reasons:
1) Maharaji was not the Lord, and 'his' Knowledge was nothing special; so I should leave.
2) Maharaji was the Lord, and his Knowledge was the royal road to enlightenment. Even if this was the case, still I had tried as hard as I could, so there was something wrong with me and for some reason I could never realise Knowledge; so I should leave.
3) The third possibility is that Maharaji is the Lord etc, as in (2) above, and being a mere human none of us can realise Knowledge by our own efforts, but only through his grace. Thus the old satsang line: 'Maharaji will cross the universe to come to you, but only if you take a step towards him'. Well, I had done the best I could at taking the one step towards him, and still he had not crossed the universe to come to me, so there was no point in carrying on; so I should leave.
So all the possibilities that I could see led to the conclusion I should leave; so I did. Note that my logic did not require me to choose which one of the propositions above is correct; merely that they are the only possibilities, and they all lead to the same conclusion. However, if you were to press me, I would opt for the first proposition!