you should sue, if you had losses on someone's advise.
If he put himself out there as an expert (when he wrote those articles) he created a fiduciary duty to those that read them and took his advice. Fiduciary duty is a broad brush stroke in the eyes of the law, from family law to corporate. Any losses probably have a case. you should seek a lawyer's opinion if you had major losses, and relied on ill advise.
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