If you could get enough gold from asteroids back to Earth to be able to secret it away and sell it without anyone noticing samples going missing, it would imply

If you could get enough gold from asteroids back to Earth to be able to secret it away and sell it without anyone noticing samples going missing, it would imply that so much is coming back that the gold market would tank, anyway. Everything we've brought back from the moon without a human hand carrying it there - which is nearby, in a predictable orbit, and is moderately easy to get to compared to everything else - weighs under five pounds. That's less than what a gallon of milk weighs. Asteroid samples brought back to earth so far weigh considerably less.