[x]

Ben Carson's campaign just sort of fizzled out. So did Rubio, who I guess got sick of campaigning. They didn't have real wins to show for all their efforts.

Whatever you think of him, Cruz did have some victories, so it's to be expected that he'd stay in the race. Your critique applies better to Kasich who only racked up one win for all his efforts.

[TTFX]

“Ben Carson’s campaign just sort of fizzled out.”

In some parts of New York Ben Carson beat Ted Cruz -despite Carson not running-, so he had enough to keep running a campaign based on ego if he wanted to.