While true, many folks chose not to go because of the reports of massive interest in the rally, which turned out to be inaccurate and manufactured. So they didn't bother showing up and waiting in line. Furthermore, many folks who wanted to get in to the arena could not due to protesters blocking entrances. Also anyone 65+ generally did not want to risk attending the rally as they are the most at risk group.All tickets were free and first come, first in. Nobody stole seats from people who wanted to go .... it had nothing to do with the crowd size that actually came. It’s not complicated.
Of course the left will completely ignore these factors and just assume that the poor attendance was due to some sort of massive drop in Trump's popularity. Truth of the matter is he will win Oklahoma by a significant margin like he did in 2016 (65-37)