I've been thinking about this. I estimate a few people per 1000 would do an atrocity for no reason if they were guaranteed no consequences, and the deaths if the switch is pulled are 2^(n-1)^ for the nth switch. The expected deaths will cross 1 somewhere in the high single-digits, then (since it's outcome*chance), so the death minimising strategy is actually to pull yours if the chain is at least that long.
I find that counterintuitive, because the overwhelming most likely outcome is still no deaths if you let it go. Humans, myself included, just aren't good at tracking large numbers of things like victims intuitively, I guess. a 1/1024 chance of 1024 deaths feels like less of a big deal that 1 guaranteed death even if I would maintain that it's not.
I guess it depends how far down it goes. Infinitely? Only enough for every person on the planet to be considered?
Theoretically, the correct option is to always switch down. Which, according to the original problem, would be doing nothing. So.. what if everyone just went home?
Also to consider; The people (and track) gets smaller every time. Maybe it ends?
Eventually it could come to a Joker guy who wants to kill as many people as possible, and you've given them the opportunity.
Maybe eventually you're just killing lilliputians and borrowers, so... Win win.