I would just like to join in with the others in this thread that have the pipe dream or just want to see how close they could possibly get.
I'm in a similar spot to you but thinking about 10 years out though, which would be 2028 ish. I figure even if it's a 0.1% chance or lower it's worth finding out.
I'm M24 and started at the marathon about a year ago. No college running, cross country & track in high school but nothing special, 5 min mile etc. But I also didn't commit as seriously as I think I could have. Did 3 marathons last year, with some mildly structured training and a bit sparsely throughout the year, starting with a 3:29, then a 2:59, then a 2:46. For the 2:46 I peaked around 60mpw for a few weeks. Now I'm aiming to be a lot more serious and see how fast I can get. I've gone for a bold direct jump to high mileage with 3 weeks at 100+mpw going into the New Year, a down week at 50mpw with some days off due to a rib injury, and back on track for 100+mpw this week while adding in some quality work. Ideally I can go sub 2:40 this year and work from there!
Who knows what will happen but I want to find out! Cheers to everyone else chasing the almost certainly unrealistic pipe dream.