Pool as it currently exists is in no way even close to as difficult as golf in any way whatsoever.
It is WAY harder to get into the top 50 golfers on this planet. The amount of people you are competing with to get to that level is HUGE. Due to the rewards of a professional golf career almost every person who has the natural talent to potentially get there and the opportunity to do so will put their 100% into the task. There are a VERY small number of people on this planet that put anywhere close to a 100% full time effort into becomming a professional pool player.
Then you have the game, pool is played on equipment that is far too easy for true professional rank competition. 4.5 inch pocket 9-foot tables just don't cut it, and the fact that the not quite top tier pros can, and often do knock off pro's most consider far more skilled just goes to show that the game atm does not test skill at the critical level needed to really be called a "hard" game.
When Putnam gets second place in the US-Open, over such players as Alex Pagulayan, SVB, Ralf Souquet, Lee Van Corteza, ect... that is happening because the game is played on equipment that blurs the lines of true skill. That difference in skill was VERY apparent when we saw Raj Hundal play Oscar Dominguez on the TAR table with 4 1/8 inch pockets, on a table like that Putnam does not get 2nd place in the US-Open and Raj does not manage 2nd place at Turning Stone.
Make professional pool a game played on 10-foot diamonds with 4 1/8th inch pockets and then we can start talking about pool as a difficult game, as it stands right now? No, sorry, it is not.
And then you have things like the Jump Cue, a gimmick specialized cue used for a single specialized shot that nullifies alot of the need to master kicking and shots like the masse that are WAY harder then a jump shot with a jump cue. In a game that are already easy we have this change where it is "hey, don't worry, jumping with a full length cue is really hard so jump with this short little stick, it is easy, look Robin Dodson is showing a 8 year old kid how to do it and he is successfully potting the ball on jump shots that would have been tough kicks to hit let alone make and teaching that kid just to HIT the ball on a masse would have been a long process. Those shots take a ton of skill, this jump cue makes things easier for us hacks and lets us close that gap between us and those really good players." This is NOT what you do if you want a sport that is percieved as hard.
Snooker is a hard game, it is a game that is far closer in difficulty to golf then pool is. Snooker tests you on every shot, most average snooker players miss simple shots, most very accomplished amature players still struggle to run centuries and it is a big thing when they do. Only the elite snooker players in their peak form tend to run centuries with fairly regular consistency and win the events. There is a big gap between the best snooker player in the world and the 20'th best snooker player in the world and in a race to 11 in snooker the number 1 player is a STRONG favorite to win. In pool the best player on the planet (Ralf, Wu, SVB, Lee Van, Appleton, Orcullo, whoever) is only slightly better then a coin flip to the 20th best player on the planet in a race to 21. When you take the top 5 guys from Taiwan, the top 5 guys from the Philipines, the top guys from Europe, the top guys from America, you end up with a list of 20 guys that are all almost coijn flips against each other. Those 6 guys I mentioned are all possibly the best player on the planet and this game is to easy for us to even know who the real top dog even is. And then they are players like Yang, Bustamante, Melling, Kuo, Chang, Mika, Thorsten.... Snooker type difficulty lets you know who is the best at a given time, pool type difficulty does not.
The thing tough about pool? It is tough to be number 1 because the game is too easy and anyone can upset anyone somewhat better then them with just a slight edge in the lucky rolls or the break.