Yes, that's true. In fact, that's true of all employees at all companies (just replace "trader" with "employee" and "bank" with "company").
However, we do not know that this trader was underpaid relative to other traders. All we know is that he was unhappy with his bonus. Once you join the Manhattan rat race, you'll find all sorts of ways to be unhappy with your bonus no matter how big it is and regardless of whether you are paid the same relative to your peers or not. In Manhattan, the sky is the limit as far as apartment prices go, for instance. If you want a place just slightly nicer or in just a slightly more ideal location, after a certain point that might be an extra million right there. There's a culture of making everyone constantly feel poor, especially after a transition in the 1900s where it became hip to live in the city rather than out of the city.
However, we do not know that this trader was underpaid relative to other traders. All we know is that he was unhappy with his bonus. Once you join the Manhattan rat race, you'll find all sorts of ways to be unhappy with your bonus no matter how big it is and regardless of whether you are paid the same relative to your peers or not. In Manhattan, the sky is the limit as far as apartment prices go, for instance. If you want a place just slightly nicer or in just a slightly more ideal location, after a certain point that might be an extra million right there. There's a culture of making everyone constantly feel poor, especially after a transition in the 1900s where it became hip to live in the city rather than out of the city.