Proprietary calibers all begin like that. But it's the public & sales that can make or break them.
There are many that appeared & soon disappeared.
Personally,, as a Ruger fan,, I LIKE the .480 Ruger. And it's success is not as good as many others,, but it's also held on over many others as well.
My advice is that if you find something you like,, buy it, and stock up on the necessities to enjoy it. If it "goes away",, then you can smile & enjoy because or smart pre-planning.
If it becomes more main stream,, and the necessities become readily available,, then smile as you can enjoy it knowing you are one of many that made it succeed.
I often discuss things similar to this subject with folks in the firearm industry. When you step back, and study the population, the number of guns, the number of gun owners, AND what they buy,, you can see trends.
The largest percentage of gun owners are "casual" gun owners. They own one or more,, yet rarely shoot much,, if any. Then there is the whole "military/LEO" stuff. That alone creates a large market for manufacturers. And the casual gun owners say; "If it's good enough for the Army or the cops, it's good enough for me."
Only about 15%-20% of the population are SERIOUS gun people who actually spend time, money & efforts in enjoying a lot of shooting or such. That market is where proprietary calibers are either accepted or rejected in general.
And I did mention that I enjoyed the Ruger 480. When it came out,, I thought; "I don't NEED that!" Well, I was a bit slow,, but once I shot one,, AND discovered the accuracy, the level of potential power,, I decided to own one. I still don't need it,, but now I have one & all the stuff to enjoy it until I'm no longer here on earth.