There were
two monsters fighting in the sea one time, the Curruid and the
Coinchenn their names were, and at the last the Coinchenn made for the
strand to escape, but the other followed him and killed him there.

Then Bolg, son of Buan, a champion of the eastern part of the world,
found the bones of the Coinchenn on the strand, and he made a spear
with them. And he gave it to a great fighting man, the son of Jubar,
and it went from one to another till it came to the woman-champion,
Aoife. And Aoife gave it to Cuchulain, and he brought it to Ireland.
And it was with it he killed his own son, and his friend Ferdiad
afterwards.

I wonder if owning the Gae Bolg was a bad thing? I mean Aoife lost her son and was defeated in the story and Cuchulain lost his son and foster brother.

It could be just the development of the stories that makes it seem that way now, but its hard to miss.