While Loki and Thanos were both part of this plot to invade Earth, there's an argument that says Loki wanted to lose this fight to that he could be taken back to Asgard as part of his scheme to rule the realm and there's an argument that says Thanos could, like his comic book self, be the kind of maniac who wants to die. There is, however, no argument that the Other and the Chitauri army must have been absolutely stupid to take on Earth with the Avengers present on the planet. The Other even said to Loki that he was very daring to question the apparent might of the Chitauri army, seemingly adamant that they would easily overcome "the meagre might of Earth" - but how wrong he was to question Loki's doubts. The Chitauri were stomped by the Avengers - with even the weaker members like Hawkeye and Black Widow easily taking out soldiers in close combats - so how the hell they ever thought they'd be a threat to Iron Man, Thor and the Hulk is beyond us.
