Wanted to get a new home with the gang cause they drove him out of his old home.
Wanted to scare the locals into selling their land cheap, so that he could make a profit.
Crystal Key Mansion
At the end the ghost thinks it has found an envelope in the glove compartment that tells him "where you all live." Since they don't all live in the same home, the ghost may have gotten hold of some other address entirely, which would account for why he is never seen again.
In the last story Darryl Taylor Kravitz pits Mystery Inc. against the Freeloading Ghost. Bleah. While the Scooby-Doo movies brought the Gang face to face with genuine supernatural creatures and magic, the creators behind those works did so with panache. In Kravitz's story, an annoying ghost wastes time with a love of his own voice. The author clearly likes his character but at the expense of the stars.
I give you the worst, most inconsequential issue of Scooby-Doo. Let's hope this doesn't start a trend.