Why did Loki attempt this at the beginning of Infinity War?

Question

In the beginning of Avengers: Infinity War, as we all know, Thanos and the Children attack and kill half of the surviving Asgardians. In search for the Space Stone, Thanos tortures Thor and then gains it from Loki. Loki makes a false attempt to join Thanos then instantly tries to stab him. He is stopped and killed easily.

Why did Loki try to kill Thanos here? He's seen Thanos defeat Hulk and kill half of the Asgardians, so he should logically know that a small blade doesn't have a great chance of success against Thanos. Also, even if he did succeed in killing Thanos here, the Children would kill Loki instantly.

If this was a spur of the moment decision, it might make sense, but it doesn't seem as if Loki is acting all on instinct - he's worked with Thanos before; he could've tried to pull off the "fake ally" thing.

I quite like the fan theory that Loki was deliberately trying to get Thanos to kill him in order to save Thor according to Thanos's 50/50 rule, but I am wondering if there is a canon answer for his actions.

Answer 1

Loki is ever the anti hero at this point. He’s finally doing right and he knows Thanos’ plan better than most at this point having worked with him in the past. He believes it is better to sacrifice himself and end it all before it begins. And he didn’t have any reason to suspect it wouldn’t work. He is doing a surprise attack, straight at the neck: a killing blow. Remember surprise attacks are very powerful and he did have a high chance of succeeding compared to a normal head to head battle.

Though at this point why would he try the fake ally thing? For starters he’s essentially already outed himself as an enemy of Thanos when he introduced Hulk for the fight attempting to defeat Thanos.

Loki: Well, for one thing, I'm not Asgardian. And for another...we have a Hulk.

_{Avengers: Infinity War}

And secondly he tried the whole ally, working for you thing, as part of his speech to get close to Thanos and Thanos is clearly unimpressed by the whole thing. He might have wanted to try the ally thing but when he saw it wouldn’t work decided to try and take him down instead.

Loki: If I might... interject... if you're going to Earth, you might want a guide. I do have a bit of... experience in that arena.

Thanos: If you consider failure experience.

Loki: I consider experience, experience.

_{Avengers: Infinity War}

Answer 2

What other option did Loki have at that point?

First, Thanos had already defeated - with incredible ease! - both Thor and Hulk, the strongest Avengers, so there was no hope to beat him in a regular fight.

Secondly, when Hulk attacked Thanos by surprise, Loki had just said "we have a Hulk", which reveals he was aware of the ambush, and arguably it was his words that signalled the Hulk to attack. This made him an enemy, or even a traitor, in Thanos's eyes. And there was no way Thanos would forgive that: just think of what he had just done to Heimdall. Loki must have realized that Thanos would kill him too, either directly or by leaving him there, stranded in space on a half-destroyed ship.

So he was going to die anyway. This means he had nothing to lose: why not try to have revenge, and die honorably?