We all have watched the infinity war in the film Thanos said to Toney “you are not the only one who cursed with the knowledge”. Toney and Thanos has kind of similarities like they both a have great command of knowledge and both can see into the future Thanos (because of time stone).
When Toney and Peter kill the Maw and rescue the Strange after that they got on Titan land where they made up the team with Quill, Drax, and Mantis. They all try to take the infinity gauntlet where Toney Punched the Thanos and made him bleed which made him vulnerable in order to hide his weakness he said “All of this for just a drop of blood”. This give a clue who would defeat the Thanos.
Most importantly Strange gave his life to save Stark by handing over the time stone, Strange might have seen the future, Toney taking control over Gauntlet and snapping it. But how this can relate? In the first avenger they started the film with a hand hold the glass of wine and that was Toney. Toney’s left arm has been injured many time even his suit on, he can feel that every passing day his hand is giving up.
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Let’s jumped back to Avenger infinity war when Thanos snapped his left arm badly injured which make him same as Toney and all the avenger believe that it’s only a Stark who can pull of infinity gauntlet. Thanos has already seen the Toney in the first Avenger where he defeated all the Thanos army, Stark intercepts the missile and takes it through the wormhole toward the Chitauri fleet. The missile detonates, destroying the Chitauri mother ship and stopping their forces on Earth. Stark’s suit runs out of power and fell on the earth but saved because of his suit.
This was reason why Thanos was on to killing the Toney and baldly wounded him when they were fighting on the Titan land, but luckily saved by the Strange.
Thanos never had an intension to kill the any of the avenger or guardian of the galaxy by his power if they die in course of snap effect he is ok with it but Thanos wanted to kill Toney because he already defeated him in the past. Thanos were much aware of Toney’s abilities and his passion towards protection of the world. While Thaons believe there is only a way to save the planet to wipe out half of the universe. Which he did eventually.
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To save the day Toney will get back to earth with a help of Nubela and where he will meet all avengers to come up with a solid strategy to kill the Thanos. The point is how many attempts they take in order to reverse the damage and fix everything like before. In order to pull the strategy Steve has to give up his life to kill the Thanos big sacrifice is required to own the big victory. Death of Captain America will be very upsetting. Steve lived as hero and will die as hero he will portray a right example of heroism.