Some people have no idea on what they're doing, but instead of bashing sometimes I tend to warn them and explain how valuable their identities are. Some scammers make their promotions attractive thats why they can always attract their preys.
Well, for some people their identity could actually worth less than the reward they are getting from completing such KYC's. For example the minimum wage in countries like India is about 50$ from what I remember and right now Blockchain is offering a reward of 50$ for verifying your identity. This means that a person from India would earn a monthly salary for completing a 5 minute task.