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.<p>It's fine to be proprietary. It's ideal for most business models that are products and not building blocks.<p>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.