About half of my employments started because I knew someone. Many of my coworkers, likewise. Almost everyone working for my dept at previous employer is now working for the same new company because their old boss got job at new company and hired most of his old team.

Getting position in your father's, relative, inlaws, etc. company is common in my experience.

Vast majority of political appointments (practically by definition).

Networking events (a couple a month for tech industry in Austin and Seattle) are all about getting the right connections.