From Newcomb's Problem and Regret of Rationality (with emphasis added):

Don't mistake me, and think that I'm talking about the Hollywood Rationality stereotype that rationalists should be selfish or shortsighted. If your utility function has a term in it for others, then win their happiness. If your utility function has a term in it for a million years hence, then win the eon.

So yes, if for you winning means making money, and your best strategy to do that is to take advantage of irrationality in the stock market, then you will be motivated to keep your methods of rationality secret.

If, on the other hand, your utility function has a term for others, then you will want to teach them to be rational and win.