I've been using Kagi for about half a year now, and I've definitely been very happy with it. As you pointed out, the fact that you pay for it with actual money and not with your attention (ie. ad views) means that they actually have an incentive to show you good results instead of endless walls of spammy links that lead to pages using their ad network.

People don't seem to realize that Google's not a search engine company with an ad network, but an ad network company with a search engine: the ads pay for all of Google's services, so they're incentivized to fill your search results with bullshit that you have to dig through, but that uses their ad network – every useless spam link you have visit when looking for the thing you actually searched for means more 💰 for Google.

The fact that so many big online services are ad-funded has led to the situation where people seem to believe that we're entitled to have everything for free online. While open source projects run by volunteers are definitely a thing (as is obvious considering where we are), I don't think it's reasonable to assume that every online service should have rely on voluntary donations and volunteer work, and that developers should work on your free pet service during their time off from their actual work