Reason 2: Social acceptability
Certain entertainment carries a greater degree of social acceptance compared to others. For instance, bingo is commonly regarded as harmless, while roulettes, sports betting, poker, or blackjack often carry negative associations, including addiction and irresponsible behavior.
Many people have a negative attitude to gambling, not even realizing that their passion for bingo is also gambling addiction. This case is interesting because people generally don't classify bingo or lotteries as forms of gambling.
Besides bingo and lotteries I think we could also mention the raffles, especially the ones which propose to collect funds for a cause related to charity. It's more common in smaller communities where people purchase numbers or names displayed on a cardboard to win a final prize (it can be electronics, household appliances, vehicles...) or sum of money, which is hidden on the cardboard itself, and it's only revealed once every numbers or names are sold out.
The collected funds are destinated to a cause such as orphanages, churches, educational institutions or to pay for a health treatment of someone in need. So people aren't like to accept the fact they are gambling, because they just think they are helping someone else. And this category of gambling also has a wide acceptance, even among gambling's criticizers.