One answer is that leaders may not understand the arithmetic.

Ouch.

But Russian growth has been sputtering — and you could argue that the Putin regime needed a distraction.

This is what I've always figured war to be about: fear and distraction. How many laws have been passed, contracts negotiated, and money exchanged for bills having to do with "terrorism". The author may be right that wars don't make sense financially for a nation, but our laws are passed by politicians, and politicians do what the "people" want, and those "people" are typically motivated by large sums of money. The "people" being large corporations with political, social, and financial means...and packs of lobbyists.

While I think the author's points are probably valid on a general and superficial level, I also believe there is way more to most of the wars than any of us know or could even guess. It's not just one factor. I'm not a scholar on Russia or the Ukraine, but I believe there is some social / cultural history between the two that is probably playing a large factor in the mess as well. Just like Israel vs Palestine, the truth is in the details - ridiculously religious, cultural, historical, passed down through generations, however-irrational-it-may-be details. War has never been rational though, so I put the attempt to study it and come to conclusions in the same bucket as "why humans think the way they do". We can guess and write papers all we want, but humans are going to keep thinking, wars are going to be fought, and your guess about what it all means is (pretty much) the same as the next guy's.