I don't think he was calling out exceptions. The paragraph intersperses people working in finance (or their ex-wives) with people not working in finance and draws no distinction between them.

"One client runs a division of a major international investment bank..."

In fact, one particular sentence lists both financial wealth and non-financial wealth:

"Another client with a net worth in the $10M range is the ex-wife of a managing director of a major investment bank, while another was able to amass $12M after taxes by her early thirties from stock options as a high level programmer in a successful IT company."

But maybe noahth is right, and the article is just poorly edited.