VC firms, not specifically YC, also tend to encourage monopolization when it comes to startups they are invested in. Have we not seen unicorns gobble up other smaller startups all the time?
Which is how AirBnB ruined tourist industries worldwide, caused rents to soar, people to get displaced from their cities of birth, and why they're touted as a "disruptor" in this very brief.
The end game for these unicorns is to become the cash hoard that they intended to compete with.