Do normal people do ironman?

My mind is racing. I was watching some motivational little clips from Ironman Canada and I was wondering if there are any normal people out there that do ironman events. I mean, how elite do you have to be? I get that it's a lot of work, but take backpacking for example. As in camping in the mountains with your food, clothes and shelter on your back. There are a lot of hard core backpackers out there that are out every weekend. But there are also people who only get out a couple times of year and do big scary trails and still do fine. Does the same sort of thing apply to ironman? From what I can gather, it will take about 5 months of some pretty serious training. I am not sure what the minimum time per week would be. But could I do it? Or is this a goal that I should just shelf for another decade? Or does it just get harder to do the older you get? My mind is racing at the mere possibility of it... and hey, you only live once, if it's something I want to do, why not get to it?? Like I said, my mind is racing...