Potential entrants are more likely to be deterred from actually entering an industry when

the industry already contains a dozen or more rivals and the capital requirements to enter the market successfully are greater than $$1$ million.

the relative cost positions of incumbent firms are about the same, such that no one incumbent has a meaningful cost advantage. the products of industry members are weakly differentiated and the pool of entry candidates is large.

industry incumbents are willing and able to launch strong defensive maneuvers to maintain their positions and make it harder for a newcomer to compete successfully and profitably.

the products of incumbent firms are strongly differentiated.