Personally I don't use Kagi for 2 reasons: It's not significantly better than what I already have (SearXNG private instance) and I don't really subscribe to the "everything must be paid on the internet". I'm much more comfortable running some dockers and putting a privacy barrier between myself and google, as I do for my searches, for my phones, computers etc. Of course this kind of tech solution is not an option for everyone, but I don't care about everyone :) $10 is a lot of money for me and I rather spend that on something I control like 2 VPSes.
Also I think that once things go commercial eventually they will reach a scale where they will want our data too. After all, data is like free money. A business will never say no to free money. By due diligence law they're not even allowed to. Kagi has that luxury now, but once they become big and own half a northern californian town for their campus they no longer will. That's the idea of enshittification.