For 99% of extensions it is not lucrative and probably nets 99% of developers a fat $0, because people view extensions as shit-tier fun little hobby scripts and so they built shit-tier extensions, or they build extensions that can’t be monetised.
But then you have smarter players (Honey, Grammarly) who realise that if you build extensions to their full potential, you can have a packet sniffing, network orchestrating, data harvesting, insanely powerful privileged web app that can do things most developers have never thought of.
So if you build these Uber extensions (Grammarly is the best example I think) you can make insane amounts of money with virtually no competition!
I’m all in on extensions. I’m currently building an LLM extension for developers that is a first in the market (unique concept) that is free in Beta, but a paid subscription once out of Beta. It is basically a super-privileged web app that is performing a useful function for devs that would be impossible for a normal website/service.
This means it has login/signup as well, which is an extremely rare sight for an extension (Because it’s much, much, much harder to handle auth in an extension. Seriously extension auth is horrible to implement and I think I’m maybe the only dev in the world with a working Google Sign In inside an extension)
But also the reason you don’t see many monetised extensions is because it’s extremely hard to securely setup auth and stripe within an extension, as they are client only.
So my powerful extensions are backed by things like cloud functions etc for some functionality and for checking auth/db-access/subscriptions