Earlier quoted context omitted.
Not really binary bets or\day trading are gambling, if you can afford it and have spare cash it would make sense over the long term to invest - though not in individual shares for most. As Benjamin Graham said “Buy when most people, including experts, are pessimistic, and sell when they are actively optimistic.”
My parents retired a year ago. If they'd kept all their money in the stock market until this month they'd be in a lot of trouble, and probably will be for the foreseeable future - how is that not a gamble? "You need to diversify" would be an argument against gambling in the stock market, and getting into something safer.
i.e. They are diversified over time.