Why not? The military has successfully done aptitude testing for decades, it's a quick way to see whether further investment in a direction is worthwhile. (Edited to add this, similarly if you have a budding interest in basketball but you're not going to get tall, you should probably not shoot for the NBA. Keep dabbling if you like it, but have realistic expectations, statistically you won't be another Webb, who was still 5'7". It's irresponsible for people to say keep pushing hard and as long as you're having fun you'll eventually get to the NBA.) Official tests are best but there are a few ok online ones that can at least quickly set approximate expectations. If the OP has already done ACT/SAT tests, it's even quicker to fetch the highly correlated IQ value.

I would be very surprised if people on the level of Carmack or Torvalds or Woz or Knuth or the many others I know of, famous or not, were under 2 standard deviations above average. It's absurd to think they're under one, which is just 'slightly above average'.