Random thought here, but, remember Vegeta and Frieza's obsession with immortality back in the Namek saga?
Thinking about that made me wonder... Why haven't Goku and the other Z fighters used the dragon balls to make themselves and their families immortal? It seems like a no brainer wish for me and my loved ones if I was them, especially with bad guys continuing to pop up every time.
I know the real reason why, just Toriyama never thinking things like this through, but I'm curious as to y'all's takes on a possible in universe explanation as to why they've never done it.
Also, what if you wished for immortality and then to be the strongest in the universe? Would the lifespan shortening cost be negated that way?