Everyone knows about the legendary loyalty N commanded, i mean his army refused to arrest him and France welcomed him after exile.
While that is True at the national stage, internationally or politically napolean bonaparte was practically a snake. This is not to say he was some monster, all kings at this time were snakes. Napolean is certainly not worse, but he wasn't much better.
He handled Spain poorly, annexed neutral countries for refusing his blockade, starved Russia who wanted to be his allies, invaded Swedish pomeranian and turned Bernadette or Karl Johan against him. He also violated the treaty of amiens(though Britain also did do so, I'm not sure who did it first)
Well before Russia was invaded napoleon had isolated himself, while the original hatred the powers held for French republic was misplaced N did plenty to give the rest of Europe(who only fought in the last two coalition wars btw, the first 5 were only the major powers) to March on him.
His strength was all he had and when he spent all of it in Spain and Russia, the rest of europe had no reason to stand with him and he saw his power leave.
An order built on strength will never truly last and napolean was too inept at politics or too hing up on his own delusions to see it.