How do short-term thinking business types infiltrate technology companies?

I feel like it’s a common script that most good companies eventually fall to short term focused management types who are happy to shred the company as long as they get their golden parachute.

Why does this seem to be the case? If you wanted to build a company that was more immune to this sort of thing how would you go about it? Examples and counter examples of these sorts of companies would be awesome to hear about.