Why do companies need to grow? Isn’t the original idea of investing that you buy and own a % of the company and then get a % of the profits?

These days everything is about growth. The original idea behind investing is that you bought a portion of the company and then received a portion of the profits. No where in that concept does it say that companies need to grow. I'd be more than happy with a company having the same profits year after year and getting that same small % of the profits. It would be expected that over time you'd actually expect less profit as competitors thin the profit margins, so even getting a consistent return I'd expect to be an unrealistic win.