The useful insight about DuckDuckGo, which the author misses, is that even with 0.1% market share, a search engine can be profitable. Search ads are valuable, because they appear when someone is actually looking for something and likely to buy. Almost all other ads are merely annoying interruptions.
DuckDuckGo isn't even a full search engine. They don't crawl the whole Web. The heavy lifting is done by Bing and Yandex. That allows DuckDuckGo to have coverage without much infrastructure. That's what makes the business possible without too much expenditure.
The article also sort of answers my question how a third party gets access to Bing and Yandex's indexes. I know they offer access, but how is it paid for? By using the founder's money from an exit, and then some VC money until profitable.
DuckDuckGo isn't even a full search engine. They don't crawl the whole Web. The heavy lifting is done by Bing and Yandex. That allows DuckDuckGo to have coverage without much infrastructure. That's what makes the business possible without too much expenditure.