Taking up security worker means driving a heavy truck tucked full of money. The job is dangerous by any means, you are tasked to visit stores and collect & deliver money for some rich asshole, and that attracts attention. Anywhere from your average patriot to organised gangmembers trying to make quick money. You will need to dispatch them quickly and effectively otherwise you will be robbed!
For such tasks, it is highly advised to call upon your friends to help you, this will greatly increase your chances of collecting and delivering money safely and efficiently.