That's because your pool playing friend has already got accustomed to pool and how pool is played. Moreso, if he's an adult, you will find it more hard to teach him a game to, say, a young pupal. Like the saying goes: "You can't teach an old dog, new tricks." Not that it is entirely difficult to teach at an elder stage, but the concepts are not going to be there to become more advanced.
Let me explain about the first sentence in the previous paragraph:
In pocket billiards, one's objective is to hit the cueball into an object ball and pocket the object ball without pocketing the whitey. Pretty self-explainatory for us that know this game too well. Henceforth, it's an "everybody's" game... from bangers to pros.
Let's get into carom: anybody aiming to just "go for the kill" and flatout try out on 3-cushion will get the ol', "Let's just get Bob Byrne's book or anything that has three-cushion diagrams or whatever and let's take it from there". Well, seriously, did Maurice Vignaux, Willie Hoppe, Jake Shaffer Sr. & Jr., Masako Katsura, Welker Cochrain, and Raymond Ceulemans all just played three-cushion first before learning this. They started small and then they thought outside the box and learned their way from there. To be honest with you, that's like injecting steroids and "cheating" (to a certain extent). Although it is nice to get an idea from other players... still, I find that this game is a never ending saga to find new moves. Any naysayers disagree about how straight rail is not a great asset?? Look at our very own American: Sang Chun Lee (R.I.P.).
Now here's where the controversy starts:
Torbjorn Blomdahl. YES, the guy's alien... period. I love his playing to death, no doubt and no sarcasm there. But he's the only exception to the rule. WHY?? Because he has spent miraculous amounts of time in other tournaments (I would suspect) either diagraming other's moves, talking to other pros on it, and/or spent thousands amounts of hours just going by feel and thinking outside the box on what to do. He DOES have a snooker history. But remember, what was before snooker and Carom? Answer: English Billiards.
So if any person were to still be alive from the past that would whoop everybody's ass with decent significant practice of any billiard sport or time while still maintaining their skills in tact, start pointing towards
Walter Lindrum.
Just my humble honest opinion...