Quote from lescor:
Incorrect. In the above example if the trader can gross the same on lower volume, or get a better commission rate, he can make decent money. Almost all the prop firms you read about on this site operate with that business model. There's nothing inherently wrong with it, the traders just need to know what kind of deal they are signing on to.
Your trading is a business. Like any business you should be looking at your overhead, revenues and margins. In the above example, revenues were good, but there was so much overhead that the thin margins resulted in no net profit.