I just heard that gambling is just like MLM schemes as people only loses both in gambling and MLM schemes ?
Is it true ?
I can't find any similarity between gambling and MLM system. In the MLM system you can earn money by joining someone else. They may have more additional requirement in case of withdrawal. But gambling is completely different. Here you will either win or lose. If you win, you will be able to withdraw money immediately.
So you are saying that in MLM we can only win , while playing gambling we can win and lose both

He doesn't seem to know what he's talking about

Sure, you can get some money from MLM, but you never know which one are you. Maybe you're one of the last before the system collapses, or maybe you're one of the last 50 people... I don't touch these schemes at all because I don't want a scammer to take advantage of me and make money. I don't support them and I show it by staying away from these people.
Gambling on the other hand can be fun. You can play with very little money and feel the thrill of winning. It's not like the casino wants to cheat you from the start, while MLM does. It's made to cheat you and take your money.