I think a large aspect of it started with immigration. Truthfully, I doubt that it's the sole cause, but immigrants have this 'hyper-competitive' mindset with them a lot of the time—and only for the sake of bragging to other immigrants about their supposed accomplishments they've earned. I think that it likely stems from them knowing they're not particularly special or interesting people, and therefore they seek to justify their existences by gathering as much 'achievement' as they can and then puffing their chest to make it look as if they're more important than they really are.
Often they'll just fraud it because they're incapable of achieving anything of importance, but a lot of them will also tend to whip their children into submission and misery and force them to take on a 'prestigious' career in STEM or something—whatever they think will get them money—just so they can brag to other subhuman families about their children and nice homes that they forced their children to buy for them.
So that's a large reason for the hyper-competitiveness in academia, at least—although I wouldn't be surprised if it ended up spreading to other things because of that general mindset being allowed to fester.