I’ll give Rand Paul credit for not quite having the ego of his Dad. Rand, at least, has come to realize he has zero chance of being elected president but can still be a reasonably decent U.S. Senator.
I think his dad knew he had zero chance, but if he ran every four years, he’d rake in plenty of donations.
Rand made himself look foolish running for President this soon in his career. In the Senate, he has been a mixed bag, off the mark some of the time, on the mark in a lot of other cases (like many libertarians). The bottom line is that Rand Paul simply doesn't have the experience or credentials to seek the Presidency (conservatives don't usually give inexperienced upstarts a free ride as liberals did for newly-minted Senator Obama, and rightly so). Most of his "accomplishments" so far have been giving speeches and filibustering. It's good to have a libertarian voice or two in the Senate, but let's see what he accomplishes first.
I almost hate to say it, but Ted Cruz's junior Senator status may also be one thing holding him back from having his candidacy the mass following it deserves. He just hasn't built the name-recognition and reputation outside the world of political junkies like us yet.