Counterpoint: you can't just go to Visa/Mastercard or a merchant acquirer out there and set up an account on the same terms that Stripe can.
On the other hand, you can sign up to any LLM provider and get API access on terms that are the same or better (since I'm sure they don't appreciate having a middleman and would benefit from incentivizing direct usage) than OpenRouter gets.
There is a reason why not doing your own payment processing is a thing.
OpenRouter may have some interesting things in streamlining the process of switching LLM providers, but it is indeed something easy to replicate in comparison to payment processing.
Their only value comes from the fact that the currently have lots of traffic. And I dkn't think that their cumstomers are really bound to theur servuce. They could switch to a competitor without too much hassle.
Or if one of the provider suddenly decide to forbid openrouter from using their api. Why would they do that tho ?? Well it's not like execs never take dumb decisions.
In my humble opinion, it's extremely overpriced. But then, it's just the standard with AI currently. Divide every ai company valuation by 1000 and you might get it's real value.