The GOP-e can’t corrupt or marginalize Trump, no matter how hard they try (and paying off commenters to post anti-Trump nonsense on the Internet is certainly an act of desperation). Walker was corrupted by the GOP-e almost immediately, and Cruz is finally becoming corrupted by them as well.
I think Walker and Cruz lost out in large part because they were too poor to self-finance a campaign, and partly because they just don’t know how to manipulate a hostile media, though of course we cannot excuse their actions. Trump could easily beat out the RNC in a spending war, but he doesn’t even have to do that; he can manipulate the media into exposing the liberalism of the GOP-e and their hatred towards the hardworking, whites, Christians, and men permeating America.
The Walker campaign raised a great deal of money. They had the support of several wealthy donors and a large fund raising operation.
The problem was that the Washington DC based consultants who ran the campaign burned through the money very quickly and had no coherent message for the voters.