Do casinos prey on the vulnerable? Does the state lottery? That's not where I draw the line for "preyed upon." When I think "preyed upon", I think of a con artist who is orchestrating bad situation to make it very difficult to escape from. That bar is much higher than what I see with crypto.
Preyed upon can use a multitude of psychological biases as tools for the deception. Crypto does that, it masquerades as this new exciting thing that's making a lot of people a lot of money. As any gold rush would tell you, greed will push people to their psyche's limits, they will fall more easily for scams given that the return might be enormous, friends will betray friends to invite them over to their scam being run in the midst of this chaos of greed.
It's a layered preying system it's taxi drivers suddenly making bank from crypto and telling other taxi drivers to join in (as I've seen happening in Brazil). It's a lucky hippie artist stumbling upon a pump-and-dump group when researching stuff for a residency, making bank and explaining to their family how they can also do it. The hippie then starting a community in some tropical paradise and funding it with the schemes they barely understand while helping his friends to join on the pump-and-dump.
People are more willing to join if they can see someone they know recommending them some strategy to make money. A lot of people will think it's iffy and miss out, and feel pretty down when they see others that weren't so smart joining in the hype and making bank. So they might join as well.
If you go to any poor country with internet access right now you'll hear about crypto. In ads, from taxi drivers, from tourism workers, etc., a lot of vulnerable people to be preyed upon and sustain the scam for a little bit longer.
The scammers don't really need to run the scheme anymore, it's self-perpetuating, a meme.
A stochastic system of preying upon financially illiterate, desperate and/or greedy people.
Casinos absolutely do. There's a litany of stories about casinos enabling gambling addicts by offering them free rooms, drinks, food, flights, whatever it takes, to keep them coming back because they know these people have a psychological condition which they can profit off of. It's exploitation.
Active vs passive is where I draw the line. Passively being enticing is not the same as actively coercing someone to do something. If passively enticing is considered preying, then the number of things in the world that "prey upon" people goes up by orders of magnitude. Fast food restaurants are now preying upon people by posting delicious advertising. It becomes a meaningless term.
