Home Assistant is well beyond the skills of the vast majority of people to install, set up, and maintain. And they don't want to have to maintain something like that. They want an appliance that they plug in and just works.
Sure. Most people don't have much beneath-the-skin technical inclination at all. We see this right now in 3D printing: Bambu Labs printers are popular because they're simple to use: A person can unbox it, plug it in, load some filament, and start printing widgets from their pocket supercomputer basically immediately.
But it is available as a plug-in appliance, and they're getting better and better at the Just Works aspects all the time.
And in a world where everything is relative, it's a hell of a lot easier to get started with Home Assistant than it is to get started with something like KNX or Crestron.
It doesn't have to be universal or even vaguely popular in order to be successful.
I have all kinds of widgets around me at home that are the products of successful companies of various sizes, and that are so niche that 95% of people would probably never seek to own such widgets themselves. Most probably aren't even aware that widgets like this exist in their universe. But the remaining 5%? They know about the widget, and they want one (maybe more than one).
There's ~149 million households in the US alone. 5% household penetration would require ~7.5 million widgets.
It sure is easy to imagine ways that a person and/or a company can sell just 7.5 million widgets and ultimately be financially unsuccessful, but it's also easy to imagine ways in which that would work out just fine.
But that's just meandering digression. :)
The Open Home Foundation had revenue of CHF 8,836,394 and expenses of of CHF 7,352,798 in FY 2025[1].
Is that small potatoes in a world with trillion-dollar companies? Yeah, it's certainly not ginormous. Is that successful? I personally think that it is.
I have the skills to run HA, and I despise the fact I must use it for any reasonable multi-vendor ecosystem.
I'd much rather have an open version of Apple Home or whatnot, even if I paid for it. I really don't want to spend a bunch of time dicking around with home automation - I want it to simply do what I want it to do.
But it is available as a plug-in appliance, and they're getting better and better at the Just Works aspects all the time.
And in a world where everything is relative, it's a hell of a lot easier to get started with Home Assistant than it is to get started with something like KNX or Crestron.
[1]: https://www.home-assistant.io/green/