Ask HN: Why am I willing to waste free money?

I'd like to get HN community thoughts / rationalization for the following behavior which I think is a cognitive bias.

1- I've found a unique way to get 'free' money - (I'll explain below, but it's really for tiny sums/not scalable)

2- With the money that I think I could get, I am completely willing to waste it - ie spend it in extravagant things, that I wouldn't otherwise do

Now I am sure this is a complete cognitive bias. The fact that I've 'earned' that money has nothing to do with how I decide to spend money in general.

For example, I am sure that if I got an increase in my traditional (ie not 'free') income in the same amount, I WOULDNT plan on spend it on the extravagant things.

It's almost like giving myself permission to do stupid things with that money because it is 'extra' or 'it doesn't count'

Any thoughts on how to rationalize this behavior? Any psychological theories?

PS: The 'free' money trick has to do with a trick to buy dollars in Argentina with Pesos using the 'official' exchange rate (which is highly controlled right now).