This sort of happened to me. I didn't miss out on superpowers but I did lose a lot of money. There was a raffle at the local community center and I had a couple of tickets in but I wasn't expecting to get anything out of it. One day I forgot to bring my membership card which would've allowed me to get into the community center for free. I was also too cheap to pay the 50 cents it would've cost to get in. At that age, 50 cents felt like a lot. On top of that, the title of the Mr. Rogers episode I was watching implied that he was going to time travel. I couldn't miss something like that.

According to my cousins I had won the raffle but because I wasn't there they gave hundreds of dollars to another kid. I didn't believe my cousins at first. I was pretty sure they were just messing with me. Years later, I asked the center's director if I actually did win the raffle. They told me that I had.

Not getting hundreds of dollars isn't as life-changing as narrowly missing becoming a superhero but that's the kernel of inspiration at the heart of this bit of the story.