Once again people will jump to conclusions without all the facts. Maybe the waitress gave really crappy service. Insulting service can be rewarded by an insulting tip. In which case the bill and relative wealth of the patron are irrelevant.
One of the jobs I had when very young was waiter in a chain restaurant (that shall remain unnamed) but I still like the story my wife tells about her father. They received extremely rude and poor service from a waitress and for for a tip he left a penny and a note reading: “Every waitress deserves a tip. Here’s yours: Find a new profession”. It’s possible this guy is an inconsiderate jerk or the waitress may have needed similar sound advice.
The waitress doesn’t work for the customer, its not the customers job to pay the waitress. The tip is supposed to be a bonus, when it comes, not mandatory- then its a tax.
This is why I oppose tipping unless its to reward really outstanding service.
Not only that, but it seems to me that the relative wealth of the patron is being inferred from the price of the meal. How do they know the patron was wealthy?
I read the first few comments and no one seemed to think that she gave bad service but that was the first thing that came to my mind. If the banker was just an a...hole he would have just left the $1.33 tip and left. He would not have written the suggestions on the bill. She did something or failed to do something for him to respond this way.