Well, my parents lived in poverty after the war too (they're both in their late '60s) and they were never rich. So, knowing they had to made sacrifices for everything (buying a house, paying for my studies), I feel bad for spending my money on things I don't need, because I think "My parents never had the chance of buying something nice for themselves and only had money after my dad retired and got his... uhm, Abfindung? And here I am wasting my money like this." Which doesn't make much sense, I know, but... I grew up sensing it in the family (even if my parents did their best to hide it), so it's not easy to get rid of this way of thinking.