Stealing $1.00 from a million people who won't miss it is more devious as you're less likely to get caught and if you get caught people are less likely to bother pursuing it.

But I think it is impossible to say one is objectively worse than the other. It depends so much on how the crime affects people. If you steal a million from a multi-billionaire, he might not even notice. If you scam a clueless person out of a million that they got in debt to hand over to you, that will ruin their life.

Robbing a bank is doing the former. Who pays for FDIC?