MCU: What Happened To Everyone Who Held The Mind Stone?
4. Thanos
By the time Thanos found his way to Wakanda to recover the Mind Stone from Vision's forehead, he had already acquired each of the other Infinity Stones. Acquiring the final stone from Vision completed his Infinity Gauntlet, which enabled him to do what he planned all along: snap his fingers.
Before he could do that, Thor showed up, and he used the power of all the Stones combined to try and stop the God of Thunder. Unfortunately, as their fight came to an end, Thor didn't "go for the head," which left Thanos an opening to snap his fingers and cull half of all life from the Universe.
Thanos was then shown to retire to a farm where he could relax with his withered and destroyed arm while basking in the sunrise. This was happening at the same time as half of everyone, everywhere was dusted out of existence.
The next time Thanos used the Mind Stone happened at the beginning of Avengers: Endgame. He used the Mind Stone, and the rest of the Infinity Stones within the Infinity Gauntlet to destroy them. He did this so that nobody could ever use them again to undo what he had done in the previous film. From this point forward in the MCU, the Stones no longer exist... but thanks to some time travel shenanigans, they still had a part to play...