You are right about this but also kind of wrong. I think the idea is to not listen to someone who is pitching you an mining investment, and that is the correct advice. Who would contact you with a legitimate business offer or market it to random people online? Only scammers to be honest. Every kind of mining project that was pitched to me on Telegram or even in person has turned out to be a scam from simple cloud mining scams to just scams where they take your money for investment and you never see anything again about this mining. So in this case it does not matter if we are talking about Bitcoin or crypto mining because the problem is not with what is being mined, the problem is that these kinds of proposals are most often scams. If you want to do mining then buy the equipment yourself.
I guess I failed to look at it from this very perspective, I just thought of it now and you are not far from the truth. But I still believe their are other possible ways to communicate this kind of information so that people don't feel the entire crypto industry is a scam, I mean, if I can misunderstand his statement definitely others might misunderstand him too.
I do agree with you on that, but many people are not that good at communicating in detail and online communication is even worse because often it can be misinterpreted in different ways. If I suffered from some crypto mining scam or someone that I know, I would also warn others from this kind of stuff and that is a good thing but correctly communicating exactly what that means is its own skill. If you think about average people and Bitcoin mining they are most likely never going to invest in it, because the scale of the industry right now is so huge. Unless you are doing personal mining as I said, nobody doing this on a significant scale will look for small time investors who can invest something like 10 or 20 thousand dollars or a bit more. This is a very big industry now, even building the center alone could cost many millions.
I think it is good advice that normal people should stay away from these kind of things, it should just be communicated a bit more clearly that even if there are many scammers in some industry that does not mean the whole thing is a scam.