Counting the number of people who wielded the infinity gauntlet between Avengers: Infinity War and Avengers: Endgame with all infinity stones intact was 3. Thanos wielded first in Infinity War and wiped out half of the universe. Then it was Hulk aka Bruce Banner who brought back half of the life and finally, in the climax sequence Iron Man wielded it to Destroy the bad guys and defeat Thanos. The first gauntlet was made in Nidavellir by Eitri – The Dwarf and the second gauntlet was homemade with Stark Tech. Thanos had to suffer because the power from the 6 infinity stones is unbearable. The same happened to Hulk and poorly, Tony couldn’t survive. Avengers: Endgame Director explains the reason why Hulk wasn’t strong to take the Infinity Gauntlet.
We know how powerful Thanos is by his quick defeat of the Hulk in Infinity War, so this is an incredibly painful experience, to put on the gauntlet that controls the universe. It permanently damages the most powerful beings and some of the most powerful creatures in these movies, and very few people can actually put that on and survive.
The visual development head of Marvel Studios, Ryan Meinerding came in to explain more of it. The systematic process of crafting the hand’s injury after wielding the gauntlet. He said,
When Hulk brings everybody back with a snap using the Stark gauntlet, they wanted Hulk to have paid a severe price for doing it
He continued talking about the alternative ideas that were in the consideration,
The idea of his arm being shriveled and messed up was where they were going with it initially, and I don’t think anybody was that comfortable with the visual of him fighting with a shriveled arm, so we were trying to come up with alternatives. I pitched that basically when his arm gets shriveled, he just rips his sleeve off and turns it into a sling to allow him to fight later on in the film and not have that asymmetry be something that was too odd. In the end, they worked it out fine in the movie without that concept.