It depends what we call serious. Clinton is the very problem of USA, she is corrupted, financed by Wall Street, above laws, and backed by the whole system, from current president to television, she has no will to change anything, and she will do nothing. Is that really a serious candidate ? That's what Obama is saying, like he didn't failed enough to have any significant result, the guy with all his intelligence and experience looks at you in the eyes and say : "that, that is a serious candidate !".
There is too much BS, that's why there is a room for someone like Trump, who tell about as much BS, but at least can show some strength not just to be elected, but to be a president, not a puppet. Even me (Sander's side), I can relate and agree with a few things he says. Especially, I have been in China, you can drive for hours and all the way see highways, lights, buildings, offices built in the last 30 years, based on unfair trades, with your money and at the cost of your jobs.
Anyway, whatever you think about Trump, people should have right to see candidates that they think can change and improve things. Let's people make wrong choices, try things, president fail, rather than voting for people that are not there for the people. In this sense, Trump is a serious candidate. Most are not.
Last but not least I don't think he has anymore egotism than other candidates, he's just stupid enough (or chose it as style) to show it. Why do you think Clinton want to be candidate whatever the cost (money from wall street, unfavorable polls against Trump) ?







