The gemara relates a story that the son of Bunias (a very wealthy man involved in real estate) came before Rebbe and they announced to make a respectable amount of place for an important person. Somebody else came in and they announced to make even more space (indicating the second person was wealthier). Reb Yishmael said to Rebbe that Bunias owns 1000 boats in the sea and 1000 cities on land (meaning he was much wealthier than the second fellow). Rebbe responded" from the way he is dressed I could not tell. Tell his father next time he sends his son to dress him appropriately and not in these clothes that do not make him appear so wealthy.
A person deserves a certain amount of respect, each according to what he does and his success. (everybody deserves respect as a human being, but above that level of respect there is a level of respect relative to a persons success). A person has to know his place in life and act and dress appropriately. If a person is wealthy, he should not appear as a regular person (not to say he should dress ostentatious, but he should dress accorsing to his stature).
The gemara continues and says Rebbe respected wealthy people because Hashem gave them wealth because they must have used their money to give tzedaka (as we had in an earlier gemara in eruvin that to retain ones wealth one should do mitzvos with his money). A person has success because Hashem is rewarding him for good deeds done and has expectations of that person for the future (more good deeds). If the person realizes that, he will not become haughty with his success, but will continue to do good deeds.