Remember how a large part of the plot of Avengers revolved around Loki controlling the minds of Hawkeye and other people with his the scepter that Thaons gave him (which turned out to be the Mind Stone)? Well it turns out that same scepter was controlling Loki as well.
https://comicbook.com/marvel/2018/12/28/loki-avengers-controlled-by-mind-stone-scepter/Marvel's official website has now confirmed that the MCU version of Loki was indeed influenced by the Mind Stone in the first Avengers movie, which caused him to carry out the attack on New York.
If you go to the "Loki On Screen" page on Marvel's website, you'll find the following excerpt has part of his biography:
"Arriving at the Sanctuary through a wormhole caused by the Bifrost, Loki met the Other, ruler of the ancient race of extraterrestrials the Chitauri, and Thanos. Offering the God of Mischief dominion over his brother?s favorite realm Earth, Thanos requested the Tesseract in return. Gifted with a Scepter that acted as a mind control device, Loki would be able to influence others. Unbeknownst to him, the Scepter was also influencing him, fueling his hatred over his brother Thor and the inhabitants of Earth."
I honestly thought it was just him being scared of Thanos. I suppose the sceptre influencing it's wielder isn't out of the realm of possibility.