He promoted himself in a way where people tuned in to watch him. Whether that's fans that wanted to see him win or those who wanted to see him lose.
This has nothing to do with the UFC promoting Conor.
What happened to the UFC after Conor's peak is irrelevant. Since we're discussing whether or not the UFC did the right thing in a marketing standpoint to snub Aldo of the rematch.
Do you think Conor would have been as popular had Aldo beat him in a rematch and then lost again to Nate Diaz?
We should be comparing apples to apples. I don't know why you're comparing a fast food restaurant to a fighter and to a fighting organization.
Let's compare the UFC to every other MMA organization out there. Nobody has reached the same level of popularity as Conor Mcgregor. Everyone wants to fight in the UFC, most casual MMA fans exclusively watch the UFC. UFC has promoted itself to be the biggest MMA org in the world, marketing itself as having the best MMA fighters in the world. Promotion and marketing is everything, and the UFC is doing great in that regard.