I don't think legality is a significant part of the problem – I simply doubt there is really a lot to make regardless of legality.
Most get-rich-quick schemes are really either “make a few pennies here or there, a few $/€/£ if you are lucky, a few 100 if very lucky” or “make-a-bit-slowly-with-lots-of-effort” or both. The rest not included in that “most” are even more completely bunkum, you'll never make anything unless maybe you join the pyramid and resell the scheme.
There is more easy money to be made selling make-money-easily schemes to those that lack critical thinking, than there is to be made via the schemes themselves. Even if no one you sell the scheme to makes anything, even if they all make a loss in the grand scheme of things, the scheme seller still has some revenue.
A scheme seeming illegal/immoral/both might make some marks easier to catch, as they think they are being clever by knowing that crime does in fact sometimes pay so their guard is further lowered due to confirmation bias on this matter.
Most get-rich-quick schemes are really either “make a few pennies here or there, a few $/€/£ if you are lucky, a few 100 if very lucky” or “make-a-bit-slowly-with-lots-of-effort” or both. The rest not included in that “most” are even more completely bunkum, you'll never make anything unless maybe you join the pyramid and resell the scheme.
There is more easy money to be made selling make-money-easily schemes to those that lack critical thinking, than there is to be made via the schemes themselves. Even if no one you sell the scheme to makes anything, even if they all make a loss in the grand scheme of things, the scheme seller still has some revenue.
A scheme seeming illegal/immoral/both might make some marks easier to catch, as they think they are being clever by knowing that crime does in fact sometimes pay so their guard is further lowered due to confirmation bias on this matter.