Let's start with a question. Would you rather be diving with a rescue diver, or someone with no rescue training?
Thankfully scuba diving, when done properly is so safe that it is unlikely that you'll be involved in a real rescue. This isn't a reason not to become a rescue diver though. If you are someone who likes to dive and intends to continue diving, then becoming a rescue diver is the least you should aspire to. As a parent, I wouldn't not learn child CPR & First Aid because I hope that I'd never need to know it. If something happens anywhere, in any walk of life, I would want to help to the best of my ability.
This great course doesn't just train you to be able to rescue someone, it trains you to recognise some situations developing, and therefore may help you prevent something before it happens. Along with that, it boosts your own self confidence and self reliance.
During the rescue diver course, you are taught a sequence of steps to enact, which will come naturally to you if you are ever involved in a real situation. You are also taught that you are far less likely to be performing a solo rescue, but more acting as part of a team of people, each doing what they need to to ensure the best outcome. If you are ever involved with a diving related rescue, or if you find yourself in a situation where your CPR/First Aid training is required, you will find that those skills you learnt fall into place.
If you are not a rescue diver, BOOK ON, it really is a brilliant course.