I usually buy cars for 5k or less, no collision, and don't worry about replacing the car if I had too. It would suck, but I have the cash so consider myself to be self insured that way. Why pay an insurance company to cover a low probability event that I can cover myself? The extra 5k you might get? Lottery tickets are cheaper and don't require you to be in a horrible car accident to pay out. Mutual funds have better odds.
I can't live my life thinking things will go wrong all the time, it's not worth the anxiety and is an expensive habit.
The only exception being if you couldn't afford to replace the car with something similar if you totalled it, but can afford the extra payment for collision, probably worth having, especially if your income depends on your car.
Otherwise, pocket the cash, drive safe, and live life like nothing terrible is about to happen. Be prepared and flexible if it does.
Just my opinion though, good luck!