Because our society is unjust, and you're probably going to die anyway.
"First-round draft pick" is such a useless term. In the span of only a few years, the Thunder, for instance, used a first rounder on a future MVP, one of the best players in the game (sorry, Seattle), then decided that they'd rather punt on a first-rounder completely than pay the kind of player you'd get in the late 20s.
At this point in the draft, you're not necessarily looking for a superstar. By 29, all the surefire first-division starters were gone 20 to 25 picks ago, so at this point in the draft, you're looking for one of two things: A high-floor bench player or a lottery ticket.