WARNING! SPOILERS FOR THE MOVIE "PRIMER" WITHIN!
I was thinking. If Abe's failsafe plan to begin with was just to incapacitate his past self and try to stop it all from happening, that's a pretty crappy future for himself too, I'd think. He'd have to give up his life and devote it to stopping the machine from getting built. OR he'd have to kill himself, which I doubt he'd be willing to do.
Let's say Abe never tells Aaron and he just goes back in time ONCE on that very first day. Then after he does it and makes some money on stocks, he decides to just quit time traveling forever. Everyone lives happily ever after, right? Sure, maybe. But just think about all the timelines that would sprout from it.
Abe 2 waits for Abe 1 to leave through the time machine so only 1 Abe stays behind to fill his shoes. Abe 2 then quits time traveling forever and lives his life, a richer man. But Abe 1 goes into the machine and into a totally new timeline. He ALSO thinks he's gonna be done with time traveling after just this one last time. It goes on forever until something stops one of the Abe 1s from one of the timelines.
Here's a simple illustration of what I mean:
So, with a failsafe or without, it seems like the options kind of suck. You either have to live with the fact that you created infinite timelines of the day you time traveled OR you gotta stop yourself from going in and give up your life to your double. Otherwise, you'd have to kill your double.
OR if by time traveling you don't create new timelines, you just reset reality. Then it'd be different.
Not like any of this is real, but it's just fun to think about.