Or it's the other way round: they know that Trump fans are now the Republican base and need to be catered to - and so they're out competing each other to show their allegiance to Trump and support of his ideas. But that's a self-sustaining cycle, where every such utterance confirms that stance towards the base and the leads to a further need to confirm it again, and go even further if possible, next time.
And so I think that, through that process, the base of the party is moving ever further into craziness, and that what was previously the Tea Party fringe is now the Republican mainstream. And that, therefore, that's where future leaders will be positioning themselves. Of course, this movement can be reversed through different leadership, but it will be a slow process that can also be reversed in turn.