system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do NBA teams draft highschool players so high? I know Lebron, and to a lesser extent, Kobe ended up working out, but it really seems like a huge risk to spend a high draft pick on a guy who really has only played against other high school students.
gpt
Pretend you're a high school engineering teacher.  Your students are tasked with building miniature model bridges, and your student Ann brings in a bridge that you can immediately tell is going to do well.  It's built from the best quality materials, has structural integrity, has no obvious flaws, and the craft represents someone who knows what they're doing.  You test it, sure enough, it wins the best grade in the class.  
  
Then you remember your own college bridge tests, that had advanced engineering principles, and you realize this bridge might pass those tests, too, even without Ann having gone to college.  You look them up, you submit the bridge to those tests, and sure enough, it does really well with the college tests too.  
  
Then you remember some advanced software -- used by corporations and contractors that build bridges -- that will test if this bridge will actually do well in the real world.  Now, the real world presents all kinds of different challenges, like wind pressure and direction, erosion, materials expansion -- that extend beyond just the model.  But every bridge has to start with a model, and the data provided by this software can determine if this is at least worth a corporation's time to scale up.  Sure enough, Ann's bridge does exceptionally well in many of the simulations.  
  
The thing is, Ann hasn't graduated high school, gone to college, interviewed at a company, or even have any work experience.  BUT -- it turns out, a good bridge doesn't need any of these things, it just needs to have some key fundamentals down in order to succeed as a bridge.
  
Likewise in the NBA, even with an abundance of variables that can cause failure, the model for success is the same: a 6'10" guy with a sturdy frame, long arms, quick hands, great basketball understanding & vision, excellent defense, professional work ethic, and a wicked shot (KD, KG, LbJ...).  This model comprises the vast majority of successful NBA players, regardless of age or experience (note: experience offers some improvement, but isn't a replacement for the above qualities).  There is no age minimum or maximum in that list, there is nothing holding back a 17 year old from playing the exact way an NBA star would -- it's just really uncommon.  When these players do surface, there are numerous professional tools that a team can submit the player to that can indicate the player's future performance from a statistical perspective.  Even a scrimmage with current NBA players is telling.  But, as is with all NBA players, every contract is a gamble -- there are numerous ways for them to fail.  So then why not look for the recipe for the ones that do succeed, and hire them, no matter what age they are?