Do people who have experienced difficult times tend to be more frugal, even after becoming wealthy?

I work in retail and cannot understand the disrespect that certain people have towards staff and the general store. Eg leaving rubbish on clothing racks. Throwing clothes on the ground if they don’t find their size. Is it just disrespectful?
Would you be offended if you saw your friend's phone and saw that they never saved your number as a contact (your texts just show up as your phone number)?