Every monetary investment is a gamble. Every time you trust someone you are taking a gamble. I would definitely gamble if I had 50 million dollars. I find it relieves stress. However, I'd probably gamble my money on supporting the pursuit of animal rights and technological singularity. But I would still play Poker, Dragon's Tale, EVE Online and Heroes of the Storm for fun. Like... Gambling is definitely stressful, but it's something repetitive and gratifying that I can do without drama from other people. Just me and random chance. That said - my betting limit would probably be $800 if I had 50 million dollars. Right now my betting limit is whatever I earn off of faucets. If I were to bet more than 0.0016% of my networth on something, it would either be for a good cause or for a positive EV (e.g. investments).
In casino gambling players almost always have negative expectation, while investors, if the are skilled enough, have positive expectation, meaning they have very high chances to see profit.
Gambling is "all or nothing, right now", investing is "more value, but later".
Unless if you can invest in a reputable casino/company to prevent scams, and it's hard to find a reliable one to invest.