I believe that people play
poker online for several reasons:
1) Because this is the only option in places where
casinos are not allowed or where there are no clubs to play.
2) Practicality often exists, but it is too far, you would spend a lot of money on gas and food. And a club can hardly provide buy-ins for all budgets. The chance of being profitable in the long run is greatly reduced.
3) The atmosphere in certain clubs is often quite toxic and unpleasant. There are also arrogant, cheating, negative, violent, prejudiced people in
online poker, but when it is much better when you play without sitting next to them.
4) The game happens all the time, it makes it more accessible for everyone to play.
5) You can play at several tables and several tournaments simultaneously, increasing the volume of play and reducing the bad effects of the variance.
However, I must admit that the glamor of a big live tournament is very exciting, and nothing beats the adrenaline of a face-to-face game.