From what I can tell, I don't think he has any problem finding people. From what I can see after watching teardowns of his products, the best of the best are working on his teams. Maybe the low level grunts are swapped in and out like disposable cogs but the rest of the org? I mean look at what they do compared to the competition. The engineering on their products is truly next level. Their workers are probably sacrificing a ton of their sanity and energy but still stick around.