Sometimes a movement recruits people such as pro-life, Tea Party, NRA etc.
Participating in the process is time consuming and at your personal cost. At the local level, the cost is minimal but grows at higher levels. I never attended a National Convention because the cost is very very high. My point, I would never take orders from party bosses on who I would support because it was MY TIME and MY Money. In fact, my experience was that the delegates are often at odds with the leadership.
So the TRUMP people can imagine all they want of a VAST Conspiracy to deny Trump the nomination but the reality it has thus far failed in the process and still does not grasp how party politics work (even though Trump chose to run as a Republican and not Independent).
It’s easier for them, psychologically, to imagine the vast conspiracy than it is to embrace the reality:
Attempting a hostile takeover of an organization of people who voluntarily associate with each other and form relationships over years is supposed to be difficult.