You have no idea where you are. Getting cold. Starting to rain. Punctured and riding on the rim. You're heading for the nearest house and hoping they have a phone to call for help.
Normal ending to a sportive?
Imagine someone persuading you to run a 80km race off road with over 3km ascent.
Imagine running that race with the longest training run being 8km long.
That was my first ultra. See here.
Just over a year later and I've ran the CCC. 101km with 6.1km ascent.