The incredible ease with which I spent 120$ on the rafting trip in Futaleufu (especially considering that when I was first told it would be 80$ I said “no way I'm doing that”) is part of the trip economics. You're sometimes frugal on ridiculous things, often foregoing the most basic comforts (easy examples: spending 5 hours sleeping on the floor of Aeroparque airport in Buenos Aires to avoid paying for a hostel before my 6am flight; choosing the bed on the low gallery over the common room in the hostel in El Calafate to save 5 pesos, and losing at least 3 hours of sleep because people were playing cards under me; sleeping in the plaza or in parks several times) and then drop 120$ for a one-time, 3-hour experience. In a sense it's logical- eating, sleeping and transportation are routine, continuous occurences, and represent the bulk of your expenses. Saving small each time ends up being a major swing upwards in your remaining budget. And the one-time expenditures are exactly that: unique and one-time-only. And why are you traveling, if not to have new and unique experiences you wouldn't have had otherwise. It's hard to come to a place that is purportedly “one of the three best places to do something” and not do it, especially when you do have the money. For example, I regretted not spending the 250 pesos for the 8-hour glacier boat tour in Los Glaciares National Park for a long time.
On the flipside, my conclusion from the rafting trip was “hey, that was really cool. Way too expensive, though”. I would do it again, but certainly not at that price. Still, from that day onwards, my hand became slightly less clenched with the coin, and my pocket zipper opened more easily.
I guess that like with anything else, the answer lies in the middle. And I should thank the one and only real god (the almighty dollar, of course, even though at that point in time it was scuffling) that I have the money for this sort of trip, for these experiences and these thoughts. Just being in the state of trip economics is an absolute positive, because it means I'm on a trip, and that's the place I want to be.
Just an addition from modern times: later on in the trip I fluctuated in my approach to money, sometimes spending big on the one-timers (paragliding, guided volcano tour, etc.) and sometimes not- most memorably for me is giving up on the skydiving opportunity in Buenos Aires. In several instances it wasn't even about the money itself, but the thought of “how can I spend so much money on something like that when people a family around here could eat for a week on it?” kind of thoughts. Those too came and went. But overall, I think I'm much more thrifty than most, and a lot less than some. And that's the way I like it, usually.