There is no such thing as a perfectly competitive market. I don't understand why people on HN are obsessed with this term. It strictly cannot exist in the real world.
A perfectly competitive market requires the following (this is not everything, just some):
- Supply perfectly meets demand (yep already wrong here)
- Marginal costs equal to average revenue (this means there should be effectively 0 profit for the seller)
- Zero transaction costs
- Zero externalities (can't exist)