I pay for it for my team... it's expensive to be honest, but worth it IMHO. Building it would be a ok, supporting it a pain.
If you work on a small startup, not worth it... on a Big corp with a lot of bureaucracy? It's worth it I think.
We have tried self-hosting it, but it's always a pain to allocate people on infra to do it, so I gave up and started paying for it for my teams, and they love it.
From the infra side, it’s something I don’t think makes a lot of sense to self-host. Metrics are the other notable one here.
They have non-linear scaling complexity, so they work fine with bumping up resources until they don’t and now you’re looking at queueing metrics on Kafka or something equally complicated. They’re horrible to change out because a lot of the APIs aren’t compatible and literally everything uses them.
They’re also awful to maintain. Everything uses them so there’s never a window when it’s convenient to shut down the feature flag system for upgrades or to test backup restores. People are much more accepting of “the vendor will be down for 2 hours on Saturday” than “I’m taking the system down for 2 hours on Saturday”.