So there is no data for off-chain, so nobody knows?
In the world, no 100m is not mainstream, particularly by its definition, "the ideas, attitudes, or activities that are regarded as normal or conventional; the dominant trend in opinion, fashion, or the arts." Crypto is not normal or conventional yet, traditional money is still dominant; its more a curiosity.
You make a good argument about the superbowl, but parallel your first sentence - viewership was only at the time of, and doesn't account for people present or who watched at a later date (ie., many). It's also been around for decades as part of American culture, maybe crypto will do this eventually. I don't see statistics for coinbase by country, but 73m is their total userbase.