We used to have poker competitions hosted all the time and in every tourney, there were at least 4-5 players who mastered their bluffing skills. You won't believe many times I had to fold just because the opponent was raising their stakes with such high confidence and even though I had the best hand, I just had no option but to fold.

With an ever-increasing number of players, you do not understand if someone is bluffing or not. I wouldn't call it a skill, bluffing is just bluffing. Anyways, we also had couple of legendary players who beat such guys too. Used to have lot of fun and won amazing chips.

The only games where you need pure luck is the slots.