First of all I said 90% of people here who are interested in a small Android phone, not 90% of everyone here.
Second, I feel you're trying to make me feel like I've gone insane and can't trust my own eyes by pretending that threads about the lack of a headphone jack don't routinely make the front page here [1] [2] [3] and that comments about the lack of a headphone jack don't routinely become the highest voted comments in any thread related to phones.
I don't think your point about iPhone sales holds any water, because you could just as easily show that people buy phones that have headphone jacks. The 12 mini is a smaller phone than the 12, so you could argue that some people who don't care about the size of their phone might be preferentially buying the mini! There's no way to make an airtight argument for either a headphone jack or a small phone as someone arguing on a forum, but I believe there are a lot of people who want both.
Moreover, my argument is that the removal of the jack was not done for any engineering reason, but for profit and aesthetics. Even if you are right that 50% of people would use a headphone jack instead of 90%, that's still a perfectly legitimate reason to include one.
[1] https://news.ycombinator.com/item?id=18538881