system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] About the snap...

Dr. Hulk struggled trying to snap. It was hard for him to do it. How come iron man snapped like it was nothing at the end?

While Dr. Hulk took on the gauntlet, it took him couple of seconds for him to snap like he can't do it. Iron man, snapped easily without struggle at the end. In other words, Dr. Hulk couldn't control his hand that well while iron man was stable and snapped easily.
gpt
Prof. Hulk was bringing back half of t he universe while trying really *really* hard to bring back Nat.  Tony had one focused goal, eliminate Thanos and his forces, nothing more nothing less.  That's a lot more simple of a goal and easier to think of in a Snap.