Napoleon's invasion of Russia was probably his greatest mistake. In order to do so, he was forced to extend his supply lines far too long to be sustainable. He also had not counted on Russia's famed "best soldier: General Winter." There is also the famous expression that one should never get involved in a land war in Asia. The Russians did not need to meet Napoleon head on; they simply withdrew and let the Russian winter do their work for them. The results, of course, were disastrous.

As an interesting, and ironic side note, Adolf Hitler's advisors warned him against invading the Soviet Union and cited Napoleon's disaster as evidence. Hitler determined that he knew the mistakes that Napoleon made, and would not repeat them. Whether he repeated the mistakes or made new ones, the result was the same. The failure of both Napoleon and Hitler to heed the sheer size let alone the climate of Russia proved the undoing of both.

Given the way in which this invasion turned out, it is almost impossible to argue that the decision to invade was a wise one.

Napoleon invaded Russia largely because of his excessive desire for power.  The basic reason for the invasion was that Russia was not living up to its obligations under various treaties with France.  For example, it did not help France in France's war with Austria.  This may not seem like a pressing reason to start a war.

Add to this the fact of the huge size of Russia.  It ought to have been clearer to Napoleon that it would be very difficult indeed to invade and conquer a country of the size of Russia.  Committing his forces to such an invasion proved to be very unwise.

Overall, then, invading a huge country for a questionably compelling reason is not a convincing sign of wisdom.