I am on Kagi Beta but IMO they do not have a valid monetisation strategy that I would pay for. Their current pricing model is planned to be $30 a month for an 'all you can eat' subscription, or $10 a month for a 'lite' membership that gives you 20 searches per day and then charges you $0.02 per search after that on a pay-as-you-go model (but if you check your search history, you may be suprised how many searches you actually do!). Users who join the $10 lite plan for instance and then do 70 searches a day (I hit much more than this during a full day of programming!) would get hit with an overage bill of $25 at the end of the month, as well as the next months 'lite' charges of $10.
On the 70 searches point too, if you search for "business news" and then click the news360 tab to get news results, I believe this is actually counted as 2 searches so would get charged at 4 cents if in the overages category.
When I searched up I thought maybe $5 a month, or possibly $10 at a push, but $30+ will be too much for mass market adoption in my opinion. I also think there is an inevitable situation that someone searches a lot and suddenly finds themselves getting a $100 bill after they signed up for $10 a month!
Unfortunately there isn't a way around the price too from an architecture perspective because it's a high cost engine to run - the costs are driven by the fact that Kagi uses the paid Google and Bing api's, then adds a bit of it's own index and instant answers, but the Google and Bing API's both charge quite a lot per request (c$0.015 per request).
Search quality is usually pretty good (until it isn't), and it's getting better as it's manually tweaked to meet common queries, but the maps search is pretty much unusable. The search doesn't seem to "understand" queries in the same way Google does, particularly ones that are semantically hard (despite the results coming from google, Kagi reshuffles them). The founder, Vlad, seems pretty great though and is very active in the discord community. I really wish them luck, and particularly that they manage to crack the cost/pricing challenge they have.
However I have gone back to Google with adblock as my daily driver as I just didn't get the same quality of results, and found myself going back to Google enough times to make it frustrating. I appreciate it is a beta though, and that it will only get better over time.