Pokerstars is where players who know better than just getting lucky play.
In poker being lucky results from having the skills to make the right moves. They are lucky when they know how to attract chance, and that is the way to go if they want luck to make money. This is so true of the game of poker, as variance may camouflage the fact that skills are required to be successful at this game. This is very similar to the situations in other games as well. But in poker, luck must be handled with care. Poker pros know that the more chance is on your side, the less money in your pocker.
All players like to be lucky, and would need to get some luck every time we play. But, luck is actually the opponent of a player. Check a poker room like Pokerstars for example, full of bad players. A bad player wins a monster pot and he believes that he deserved it, while he was just unbeliveably lucky. A fish player does not fold when needed, always opens up from early position, makes perfect catches, … A bad player can hope to get miraculous cards at any time. So, they are considered to have more chance then other players. They have various ways of obtaining luck.
Great poker players by contrast count on their opponents to shoot themselves in the foot, and not on luck. This is the simple way to win. So if a fish calls the bets from a profitable tough player when it is time to run for the exit, this is negative EV for the bad player. It does not matter if he hits the draw or not, in the future he will not be profitable.
At pokerstars there are many fish and just a few sharks. This is a nice pond for fishing if you have not tried playing online poker there yet.