I just listened to a podcast with Patrick Collison in which he listed the ways in which Stripe's market seemed unattractive when they started out. Dauntingly complex, highly regulated etc.
Anyone looking to compete with Stripe will have the same thought process and probably won't bother.
And if they do then they will have to execute as successfully as Stripe over an extended period.
Edit: Just to add that the podcast was "The Knowledge Project" [1] - just a fascinating conversation.