Let me put it this way.
To be the goat you must have been the best at some point, have won a lot and have remained competitive for a long time.
So you end up with 3 people.
GTR was in a weak era so that means it cant be him and he wasnt really competitive for the last half of his CSGO career.
Cold, hes was the best for 2 years when CSGO was full of great teams, he won 2 majors and remained a good player for a few years after.
Olof, was the best for a year, won 2 major, however in an era with more major, was also an good player in 2016, 2017 and 2018.
Devices level hasnt really changed his entire career which is amazing but hes never broken into the number 1 spot, hes won loads but hes never been the best player in the world while doing so.