Trump

Gleaned from many comments:
He's gone bankrupt a bunch but this could be a bug (bad management) or a feature (the guy will rescue Washington when the money's gone).
The media will chase Trump stories to suck oxygen away from strong GOP candidates.
He's a stalking horse for the Democrats, see quote below.
He puts being rich on the table with lots of his own money and shows Hillary is a phony who won't be honest about her own money.
He's one-dimensional about success and defines it in dollars.
Few take him seriously but most say he's better than Barack.
Along with Fiorina, he makes people wonder if business instead of law is where we should look for politicians.

And one of the most thoughtful observations from Wintermute:

"I know there's a deep desire to have a messenger that speaks his mind and promises bold things for conservatives...I have that same desire...but be very, very wary of Trump. Most know Trump these days through his reality TV career. But those of us from NYC have known him for far longer.  First, he's not a conservative, he just plays one one reality TV."    (read the rest)

Trump is a sore loser and could pull a Ross Perot, running as a third party, putting Hillary in the catbird's seat.

From Andrew Malcolm: (Writing for Investors.com)

Trump's well-financed game of political pretend will get much undeserved media attention in coming weeks, just as showman P.T. Barnum's hoaxes did. But Trump's ruse is damaging, as intended.

Trump is in reality a stalking horse for Democrats, including the Clinton couple, who ruled the last time our nation endured a reality-show presidency. Trump has contributed countless thousands of dollars to re-elect and curry favor with the Clintons, their foundation and other Dems.

Hillary is his pal. So, suddenly he's Republican, which helps her, feeds his ego and hurts the GOP. Win-win-win for everyone on that side, especially Trump,