Other bottom line is that once nominated the Republican party opens its’ coffers and lists to the nominee. Trump could raise $1 billion as easy as anyone, perhaps easier.
It is also likely he has a dozen friends who are also billionaires who would likely open a PAC giving him more than $1 billion to destroy Clinton.
There is no doubt in my mind that Trump is the most feared adversary because of his own money, his access to more money, and his name recognition.