Gambling is a game of try your luck ,a game of chance if you can win to make more money or valuables for yourself, getting rich quick.
Yup, when things didn't went according to your expected outcome especially when you're done with your research, when you think that everything is moving according to how you expect but it turned against you when the outcome was announce, there are many rumors that circulate and the gambler who lost their bets surely thinks that they've been scam.
I do not think gambling is a scam. It would be extremely selfish for a gambler to believe that gambling is a scam only when he loses but then he gets paid when he wins. If a gambler is paid for his winnings, this cannot be considered a scam. I also know that there are scam betting websites that never pay out winnings. Only deposits are permitted, with no provision for withdrawal of winnings following deposits. Except in these cases, those who gamble on a reputable betting site cannot claim to have been scammed simply because they do not win. This is because, in most cases, a person who wagers any amount should be aware that it is a 50/50 chance that they will win or lose.
Another reason why gambling is called a scam is that gamblers mostly lose from reputable casinos or gaming sites as well as betting sites. You can be confident in getting your money back from reputable betting sites but some others are unreliable. I consider the trustworthy side when betting which is confident in getting money.