12 Really Stupid Decisions In Comic Book Movie History
2. Loki Banishes Odin - Thor: Ragnarok
Loki is - somewhat famously - driven only by the endgame that sees him as powerful as possible. If he makes any alliances, they're done in service of that agenda and every time he flip-flops on being good or bad or completely morally non-binary, he's just trying to advance himself.
He probably doesn't always think straight while trying to achieve that, because power is intoxicating even to the smartest characters, but that doesn't justify him kicking off Ragnarok and destroying Asgard indirectly because of his need for more.
That's what he does by tricking Odin and banishing him to Earth, because the All-Father's absence frees Hela and leads to the genocide of the people he briefly ruled. Removing the protector of the Nine Realms and replacing him with someone he knows so intimately is a liability - since he is him himself - was not a smart move.
In fact, calling him a moron is too good for him.