On the other hand, it did teach me the true cost of searches, and I use a lot more !bangs now, like !mdn or !archwiki (although the search powering both of these are probably funded by donations)
It really does change the dynamic of how you search, if you know that the next search will cost you 1.25¢. Right now I use Ecosia, so I'm actually more motivated to do extra searches, to increase the number of trees they plant. Kagi is the other way around, search has a cost, so be mindful about what you search for. It's a great way for them to have a sense of their load, while also perhaps being ever so slightly more sustainable.
Ecosia and Kagi aren't targeting the same market. Ecosia, for example, isn't as serious about privacy: https://news.ycombinator.com/item?id=25713050