All lives are not equal. The value of the life of a thief whose only impact on the society is negative, cannot be compared to e.g. a doctor.

Do you also define yourself according to the worst thing you've ever done?

So why would someone risk his live and become a thief instead of a doctor?

Some combination of desperation and sociopathy.

I might suppose that it's usually more the former than the latter, but there's degrees to each characteristic.

They perceive that they need things, and they don't necessarily care who they harm to get the things that satisfy this need.

(When we dress it up all nice and back it with corporate layers and an army of lawyers, sometimes we get CEOs.)