Because you people are hysterical and overreact to everything. First it was Cruz's win in Wisconsin that was CONTESTED CONVENTION GUARANTEED!!! Now this and its a guaranteed Trump nomination. If you actually work through the math, as I've been doing, its still very possible to find a way for Cruz to stop Trump. I wouldn't extrapolate his crazy weak performance in Northeastern contests to other states. I think Trump is favored at this point, but he's not a strong front runner by any means. I'm not one to brag, but I'm pretty dang proud that I was highly skeptical of Cruz winning the nomination from the beginning of April.
Sorry, that's my rant. I'm just so sick of the prognosticators on this forum having the mood swings of a teenage girl.
The biggest reason to be bullish on Trump right now is that he is gaining in the polls in CA. We can't expect him to underperform polling anymore, and since it is WTA by district even a narrow Trump win would get him enough to win on the first ballot.