1. Loki is totally convinced of Asgardian superiority in general and royal superiority in particular. A couple of guards dying is at most a necessary sacrifice to reveal Thor's ineptitude, but humans and frost giants and other species are like paper towels: there to be used once and then thrown away.
2. He sincerely thinks he's a monster and, depending on the situation, operates under the influence of either extreme internal racism (the attack on Jotunheim) or the belief that since he's a monster he should act like one (refusing Thor's offer of redemption). He wants to feel superior again, so he lies to Thor about the situation in Asgard to make him feel like the inferior son for once and tries to take over Earth so he can force people to respect him.
Re: CHARACTER ADVICE - Loki (MCU)
2. He sincerely thinks he's a monster and, depending on the situation, operates under the influence of either extreme internal racism (the attack on Jotunheim) or the belief that since he's a monster he should act like one (refusing Thor's offer of redemption). He wants to feel superior again, so he lies to Thor about the situation in Asgard to make him feel like the inferior son for once and tries to take over Earth so he can force people to respect him.