Maybe it is the nature of a person, eager to win while losing and also we have the mindset of not giving up and in the end we either lose our money or get it back and win more of it
Yeah greedy nature is the only responsible factor for going back to gambling again and again even after loosing at majority of times as its a human nature to believe that he will win in the next game which makes him to visit gambling sites regularly hoping that he would be able to recover his loss but unfortunately that never happens and its only the house who keeps on winning at the majority of times.