Well yes, it's completely arbitrary! Those with the luxury to act irrationally will sometimes do so, I guess. And economics doesn't do a good job of explaining it, so the root of this branch of the comment tree was kinda right when they said traditional economic theory is a ass.[0]
Adversity and scarcity breeds a precision and a ruthless attention to detail that prevents that $50 from escaping. Meanwhile abundance leads to a relaxing of all such, and maybe even a dulling of that skill. Being born into wealth I imagine would put you at an even bigger disadvantage in that regard... though I might be okay with having such problems...
The reason why people act irrationally has more to do with psychology than economics. Vsauce has a good segment talking about human tendency to think in terms of proportion instead of absolute scale: https://youtu.be/Pxb5lSPLy9c?t=1m53s
Adversity and scarcity breeds a precision and a ruthless attention to detail that prevents that $50 from escaping. Meanwhile abundance leads to a relaxing of all such, and maybe even a dulling of that skill. Being born into wealth I imagine would put you at an even bigger disadvantage in that regard... though I might be okay with having such problems...
[0] I'm paraphrasing of course and I changed Law to Economics. http://www.bartleby.com/73/1002.html