Another issue I feel like that largely goes unnoticed is, privacy in incognito mode, if I use kagi in incognito, all my searches are associated with my "account", even worse for some people their payment information!, which is something I'm just not comfortable with.
EDIT:
So I thought about it a little, and I'd say 10$ a month is probably worth it (to me)! Just for the features and search result quality. Considering how much of a value a search engine has in my life. I was initially skeptical if it would cost them THAT much. But I see it from a different perspective now.
I would still not use Kagi for private searches though, and that's just me. Privacy is something I would rather trust someone without my full name with, that just my opinion though.