I also thining about it sometimes... I think that people scam mainly because of easy money. They only want to earn huge money with the low cost of money and energy. Crypto world is even easier way for them to do this because of more anonymity, decentralization and you know.
They also scam because of discontentment. They are not contented with waht they have that they are willing to do harm to other peopls for the sake of money. Yes your right, cryptocurrecies provide anonymity for the users that is why it is very vulnerable for theft attack and scam. It's very risky to transact with other people.
Being not contented with what we have is not good. The purpose why they scam other people is being greedy with the money. They thought scamming people is the easiest way for them to earn money. They do whatever they want as long no one knows their identity.
I would say it's more than greed. It's incompetence. Millionaires are also greedy, but they have the competence to create or invest in demand-generating projects that spread all over the world, creating business models that have been in place for decades.
If these scammers had the competence and skills that great entrepreneurs have, they would certainly choose to create a sustainable business model, since there would be money to be made.