It is not a delusion. It happens all the time.

For example, 3 months ago developers of GZDoom didn't like where it heads, so forked it to UZDoom (vide https://github.com/ZDoom/gzdoom/issues/3395 and https://www.techspot.com/news/109864-gzdoom-developers-split...).

The core part is if you can find enough contributors (from the original repo, or new ones) to make it viable.