Gamblers may need some reason until getting addicted. Most gambler use "I just gamble occasionally then why not" or "I gamble for fun, why not" or "I just gamble my excess money after all my budget". But, these reasons are insignificant for preventing addictions and these gamblers may get addicted at any time.
Once got addicted then no reason is needed as they never bother anyone including themselves.
Gamblers honestly do not need any reason for themselves but they need to carry one so that they could justify themselves in front of others. Yes, reason is needed for the sake of others and this is why most gamblers are having highly stupid reasons.
That can be a valid reason for some gambler, to have fun and to seek for some entertainment, but sometimes that entertainment becomes a hobby that triggers you to become addict.
I never believe into the gamblers who are all claiming that they are gambling only for the reason of finding entertainment. Because, there are a lot of other methods and industries are available to engage ourselves for free to fair charges. But these people are preferring only gambling. Why ? Because they want to win some profits (that must be their ultimate goal hence keep trying). Then how can be sure about they are gambling only for the reason they are stating.