To be fair in the sort of tournament held at the Palace recently, whilst Pool can and is played by a number of people of all shapes and sizes, you would be surprised how mentally challenging it is to play over perhaps a 15 hour day. Like anything really.
Many people in these types of events (and Darts would be another example) are taking things more seriously these days. Where money is involved, over time, it will change the way people approached the sport or game.
Golf is a good example of this. Snooker another. Darts perhaps changing over time.
The darts festival here is one of the main events outside of the world championships on the BDO circuit.