I think she spends too much because if she wants it, she buys it. Cost is a very minor consideration. She is the youngest of 6 kids and was given most everything she wanted. I on the other hand am the oldest and was raised in a very modest household.
She gets almost giddy when she has something new. That bothers me because she seems to try to buy her happiness. It also bothers me because I am frugal about my needs and she is extravagant about hers. I would rather save money on minor things to spend it on longer lasting, larger items (Cars, house, toys). Things that the whole family and others can enjoy not just her. The other isssue is "timing", she buys it when she wants it not when we can afford it. We have a beautiful new home, nice cars, and I am still paying off my entry into the firm. If she would let me get caught up she could buy most anything she needs. I tell her to have patience and that the time will come. It is more about pacing, patience, and discipline. I also don't want our boys to think that just because we can afford it they get to have it. That sense of entitlement scares me and they need to learn to work for it. I will support them until they graduate college (5 yrs or less) after that they are on their own. I have seen too many of my client kids rely on their wealthy parents too much. There is my rant for the day.
You bankers are always "conservative" about your earnings. You seem to forget that I am a CPA and I do have several banker clients.