To answer your question brainiac.
Sony was willing to play ball.
Nuff said.
Sony was willing to play ball.
Nuff said.
Ummm,
They also don't own the film rights to Spiderman.
And yet; this didn't stop Marvel from working with Sony to have Spidey appear in Civil War, Infinity War and Endgame. Nor did it prevent them from co-producing 3 solo Spiderman films, a cameo at the end of Venom: Let There Be Carnage and another as yet titled future Spiderman film. And let's face it, these Spiderman films have ALL been financial blockbusters. (With No Way Home being arguably the BEST recieved Spiderman movie of all time...)
And technically, they DID sacrifice both Cap & Ironman at the conclusion of Endgame. It was Ironman who sacrificed himself to end Thanos. In fact, it was Tony Stark who made the BIGGEST sacrifice of all. Or don't you remember his final line before snapping Thanos out of existence: "And- I -Am -IRONMAN.".