Indeed, I agree with you, my friend, in what you mentioned, maybe the others can say that MLM is like gambling because if you don't succeed in joining MLM and you don't earn anything, you also lose like betting on a gamble, it's like that's what they mean. This is just my own understanding.
Generally, what they compared here is losing money although it should be obvious that comparing MLM and usual gambling doesn't make any sense and is not appropriate even how to try we compare these two. Gambling and MLM have different systems and way of winning/losing.
However, we can't deny the fact that most MLM is a failures that's why the risks are almost the same as people losing money in gambling.
Whatever our view, just be wise next time and study very well what investments should we put at risk especially joining MLMs.