Jtdcftul

(SPOILERS ahead - for the ones who didn't watch it yet)

In Avengers: Endgame, we learn that Thanos destroys the Infinity Stones. And then, the Avengers go back in time (perhaps to different realities) in order to gather Infinity Stones. Once they finish their work with these Infinity Stones, they are taken back to their respective realities. So, in the main timeline, where they bring back the dusted characters, there are no infinity stones.

But, consider the Time Stone. Doctor Strange and his sanctum swore to protect the Time Stone.

Then, why did Doctor strange give away the Time Stone to Thanos while it's anyway not there at the end of Endgame ?

Then, why did Doctor Strange give away the Time Stone to Thanos while it's anyway not there at the end of Endgame ?

What other choice did he have?

Of the 14,000,605 outcomes there was only one way to win.

Strange had to give up the Time Stone to let the remaining Avengers on Titan continue to live (Thanos would have killed them otherwise) so that ultimate victory could be achieved.

If Tony Stark is killed by Thanos on Titan during Infinity War then he can't be there to complete the victory in Endgame.

Once the final battle is over, Captain America returns the Time Stone to it's proper place in the timeline (with The Ancient One) who will eventually leave it in Kamar-Taj for Doctor Strange to "inherit".

Then, why did Doctor strange give away the Time Stone to Thanos while it's anyway not there at the end of Endgame?

Remember that Strange had seen 14,000,605 possible futures in Infinity War and was trying to bring about the one scenario where they won.

If Tony dies in Infinity War, he doesn't

solve the time travel navigation problem that they have initially in Endgame.

If someone else fixes that, he's not around to

come up with the idea of jumping back to the 70s to try and regain the Tesseract and more Pym Particles after the trouble they have in 2012.

If someone else thinks of that, he's

not there at the final fight to grab the stones off Thanos and carry out the final snap to destroy both Thanos and his attacking army.

Tony was absolutely key to the single winning scenario. As Dr Strange knew this already, he had to do whatever was necessary to ensure that Tony didn't die in Infinity War.