My sister in law recently ran a 50 miles marathon so I guess I can't call you insane.
If you have to carry a flashlight to run a marathon, something is wrong.
Those 50 mile marathons are crazy. If you have to run 50 miles, something is wrong. If you WANT to run 50 miles, something is seriously wrong.
I ran regularly when I was in high school and college. I used to run in the Capitol 10,000 and some 5Ks. Now I have a bad ankle that craps out on me if I run for any significant distance.
I never understood why anybody wanted to run a marathon, much less a 50 mile one. I never had fun running. None of the people I ran with looked like they were enjoying it either. The only "runner's high" I ever got was from running by some Rastas smoking weed on the sidewalk.
Cycling is at least exciting - a violent crash is always just a small mistake away, sometimes you get to go really fast, and scenery moves by fast enough to keep you from getting bored. The randonneuring thing doesn't sound too bad.