Okay, so what this means in context is 'that many financial advisors make inefficient decisions that prevent them from getting all of the money they can from a situation.' You have probably had difficulty understanding this expression for two reasons:
1. "small fortune" is something called in English an "oxymoron." This means that the author or speaker has used two words that contradict one another. In this situation, "small" means "something of little amount or size" while "fortune" means "a large and great wealth." The reason this is done in English is hard to explain, but "oxymorons" usually have a slightly humorous meaning and can sometimes be sarcastic. I do not know if sarcasm translates to all other types of culture, but that is often the intention in English.
2. The second difficulty is the expression "on the table." This is an expression often used when a business deal is being made or the options of a decision are being discussed. This is an appropriate expression for the business article you are reading. It is meant to make you think of a business situation where money is offered and placed on the table between two people making a trade deal. Your article is saying that some people do not always achieve the best deal they are capable of.
I hope this analysis helps you.