The reason why it's "laughable" is because the amount of smug confidence going around is pretty toxic to conversation.
Look, I get it, Hillary is going to win tonight. But exactly how big is the question on a lot of people's minds.
To outright declare the end of someone's candidacy and in such a way that almost seems to try to get people to stop talking about it isn't cool. We have a lot of supporters on both sides, and we all want the same thing, right? A Democrat to keep the White House. I'd figure we would want to be more sympathetic to those other's candidate who might have a less of a chance winning and be inclusive in wanting them consider switching support when their time is right.
And my time will be when I think Bernie has zero chance. But only when I think he does.
There isn't any smug confidence when it comes to Hillary and her chances of winning. The confidence comes from months and months of polling data and knowing how the American electorate think and vote.