I could not find a good source of all the projects that changed their licenses after they became "successful" and stop being Open Source. I am sure we can gather a nice list here
A lot of OSS founders make bold claims to their contributors and donors like "oh we'll never take XYZ feature away or charge for our services". Until they do.
It's fine to be proprietary. It's ideal for most business models that are products and not building blocks.
It's better to start as closed source, then go open if you feel it's a good route for what you're building. You'll piss less people off that way.
Well OpenAI (name's a clue?) but the Rift is something I seem to remember from when they crowdfunded the launch. It blew up when it transitioned into closed source after taking money. But my memory could be playing tricks here.
It's fine to be proprietary. It's ideal for most business models that are products and not building blocks.
It's better to start as closed source, then go open if you feel it's a good route for what you're building. You'll piss less people off that way.