yes, sir very beautiful post about cactuses plant, I too have never seen these in such number at one place, I think this man sell these plants. I do remember I have seen these once in the park near my home, but they are not in such number, maybe one or two plants at one place. Be careful boy its needles can cause you sware damage, so never ever go near to plant like this. haha you said it right, when we don't have much information about some specific topic or some specific person, we judge him by his look, by his clothes, and by his behavior, outer look can't give you exact information but it can give you basic information that is needed to know. But there are some people who are very beautiful from outside but they are very cheap, here we can be mistaken sometimes, but this is how life goes. Take an Example of these plants they look dangerous by their outer look but they can't harm you if you don't touch them or try to mess with them.
Thank you for sharing wonderful information about cactus. God bless you @velimir.