If the average payoff is negative, but the payoff is tied to a catastrophic event, then it's insurance. Risk mitigation is a valid part of investing.

Gambling has a negative, random payoff.

Occasionally, a large jackpot can return a positive average payoff, if it's powerball style and they accrue from round to round. However, the odds are so astronomically against any one ticket winning, that it would still be considered gambling. If a billionaire could risk enough of their fortune to gain a high probability of getting that winning ticket and therefore making an overall profit, then perhaps it would be investing from his perspective, but if you or I blows our $50k emergency fund and still has a 99% chance of losing it all, it's still gambling.

This is kind of a crude definition. If you knew a certain slot machine in Vegas had a positive expected payout, sure, you'd be rich, but is it an investment? Also, there are plenty of people legitimately investing in companies that have less than even odds of a return.

Investing to me is more about mindset and the manner in which you deploy capital for a return, and how much you are relying upon luck, guesswork, and chance.

Gambler's ruin applies even in circumstances with positive expectation.

That's not true. Investments can fail.