Taking a common-sense definition of beginner / intermediate / advanced, I'd say very few players who stick with the game a couple of years fail to make intermediate-level.
Almost by definition, intermediate is most players with any experience.
So the big jump is intermediate to advanced.
And again, the definition of advanced is shaped to be a fairly small proportion of players. (If most players were advanced, advanced would mean average.)
So for players who want to improve, the question is how to go from intermediate to advanced. (Then later, maybe you can think about advanced to pro.)
I think you can get to advanced with correct fundamentals and practice time, and you'll struggle to get to advanced if either is lacking (although naturally talented poolhall bums with bad fundamentals do manage it with just time).