Why Would the Democratic Party Nominate Someone Who is not a Democrat?

It's such an obvious question. James Carville asked it last night on Chris Hayes. 

Bernie's alleged path to victory frankly is so fanciful as to not avoid the laugh test. It is also laden with hypocrisy as he spent months fulminating about super delegates voting against the will of the voters and is now asking them to do just that if Hillary won the state. 

http://www.realclearpolitics.com/articles/2016/04/04/clinton_has_25_million-vote_lead_so_who_is_more_popular_130182.html

But this makes you realize how unlikely it is that Bernie wins over many SDs. These are the same party members who has denigrated for months as the 'Democratic Establishment' as if it's something dirty. 

He still refuses to lift a finger to raise money for any Democratic races. 

He has admitted that he only ran as a Democrat for the greater publicity. 

So where are the carrots that will make a SD jump from a real Democrat who has raised lots of money for Democratic candidates to Bernie who is not a Democrat who has always had contempt for Democrats and is all about himself as usual. Ralph Nader rightly called him a lone wolf. 

Lone wolves are hardly what is needed to get Washington working again. 

One other pet peeve. The primary is not 'tied' because one poll shows it thus. The averages have her up by close to double digits and have for months. 

In any case, why look at national polls at all now? Why would you call people in states that have already voted rather than look at how they voted?

Looking there shows Hillary up by the landslide margin of 58-42.