It is your decision, but if it were me I would trust the surgeon. The odds they give you of something going wrong are very low (and they exagerate them a little to be on the safe side), and if it is a recognized surgeon and hospital, those odds would decrease even more. As your Dr says, you are in good shape and taking care of your body through the years is now your best ally. I had my surgery at 5.2cm, surgeon recommended I had it as soon as possible, as it was large for my body size and there was a history or aneurysms in my family. It was found by chance while prepping me for leg surgery after a bike accident, for me the stress of knowing I had one was way stronger than any fear I had of surgery. Being in good shape helped my recovery, I was out of the hospital in 5 days, back to work in 3 weeks.

When I was about 14 my nextdoor neighbor collapsed at the side of his house, he was moaning in excruciating pain, he was alone, so I jumped the fence to help him as my mom called an ambulance, I struggled but managed to get him inside and on his bed, he was awake but you could tell the pain was overwhelming and made him unresponsive. He passed 2 hours later at the hospital, he had a large AAA, he knew but in his case he was around 80, the odds they had given him were low. But that was decades ago, medicine has come a long way since. When my time came, they gave me excellent odds, I did not doubt, I had surgery 3 months after leg surgery as they want you walking right away.

Wish you the best!!!