Are the results really that much better? I use DDG and paying $10/mo for a search engine seems like a tall order, especially when I don't know if Kagi can be that much less broken than Google.
I did not do an extensive comparison to DDG but I would say it is definitely worth it. Been paying for awhile now and it blows away Google. And they are constantly adding new features and improving old ones (and finding new ways to improve their back end costs as well which makes it more sustainable).
I use search engines a TON though (especially for work) so 10$ a month is absolutely worth it for me. I am currently trying to convince my boss to buy it for our whole IT team
For technical info like programming language references, I get much better results in Kagi after I spent a few minutes setting my blocks and pins. I just searched "run a test suite in go" in Google, DDG and Kagi, and blogspam results were higher in Google and DDG while GoDoc and Stack Overflow was higher for me in Kagi. Many of the DDG results were about running a single test out of a suite, rather than running a suite.