> Can one make a living selling their Linux applications to end users?

There are companies that do this- DaVinci Resolve, IntelliJ IDEA, Ardour come to mind.

While I wouldn't quite call it prominence, nor can I imagine you could make a living with it exclusively, elementary OS has something of a Linux app store with their AppCenter. Flipping through the website it seems to offer developers the standard 70/30 split.

It's quite simple, the market for paid end user applications on Linux is tiny. Canonical was saying years ago that they were going to add paid applications to the Snap Store but seemingly never got around to it. Elementary's App Center has integrated payments but they are optional and ~99% of users do not pay anything.

You can certainly make a living selling a cross platform application that supports Linux, but it's probably quite difficult to make much of a living selling Linux-only applications.

I think an app store would be a great location to not have optional payments for open source software if developers do not want it. Users can choose to go get and compile the source, download a third-party binary and keep it updated themselves, or pay for it and know it's directly from the authors and automatically updated and getting a path to support and the interested customers know the only people submitting reviews are people who paid for it and not drive by opinionated users like is common in open source software.

I'd say the existing app stores plugged on distribution repos (apt) provide a very large amount of free software, thus reducing the incentive to look for paid software.

For the seller, being able to sell is one thing, having to run software in a tiny and extremely fragmented market (a large bunch of slightly different distros) is another one. Then osx happened, and the linux desktop never happened.