"Kagi is building a novel ad-free, paid search engine and a powerful web browser as a part of our mission to humanize the web." With 670K? Cuil went through about $30 million to develop a standalone search engine. And that was fifteen years ago, when search was simpler. There may be a market for a search engine company that profitably runs a low-cost operation with very few ads and makes real efforts to keep out spam…
As someone who has already replaced Google with Kagi, as far as I'm concerned they've already done it.
I've never paid Google for anything (apart from with my data) but I've been paying Kagi for almost a year now. The model is different. From what I've seen so far, it's better.
The amount of money you burn through is not a good indicator of whether you'll end up with a good product or viable business at the end, IMHO