I dont think it is needed to add because I doubt there is someone who jumped into gambling for the first time solely because he wants to get enteratained. This is a fact because most people gambling because of money oriented reason, fun/entertainment is just small part of gambling and it is usually come later not on early stage. Anyway, I voted for social influence although maybe it is also close to early exposure about it since gambling was an activity that being done by most people in my village. Starting from real dice game and sports betting (against other) and lottery. Due to these fact, curiosity come to me and lead me to try it myself.