It seems I'll have to answer my question on my own. Namely, it's certainly so that stupidity is one of major prerequisites for becoming a pres: why listen to advisers when one knows everything better...?

Spies Warned White House: Don’t Hit Al Qaeda in Syria
...“If the U.S. attacks Nusra without attacking Assad, all the average Syrian sees is that the U.S. is enabling, emboldening, and strengthening the Assad regime,” said Christopher Harmer, a former Navy officer and an analyst with the Institute for the Study of War, which monitors developments in Syria. “It’s not that the Syrian people love Nusra; it’s that Nusra has been in the fight against Assad, and the U.S. has looked for every excuse to stay out of the fight against Assad.”
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This is imposing the question: why paying advisers? How about firing all of them and saving tax-payers plenty of money...?