Gambling is never an investment since its just a game with money involved unless if you decide you put your money to the house itself then its considered an investment and with that its somehow safe compared on playing gambling itself because you are on the house side which we all know who always wins therefore we could say that we could able generate profits when house is profiting too.
IT is correct, I never consider gambling as a type of investment although there are many people think that it is. In general, gambling is just a collection of games which closely relates to the luck. While gambling, you can have some extra profit, however, you can never beat the house edge. They will always know how to obtain money from you. That's not what investment is.