This means that they just need to sell enough advertising (which I think bing provides / forces them to use) so basically for DDG, more visitors = more revenue and breakeven means that the traffic pays for the costs they have.
If I were to create a privacy first search engine, I would likely not go general purpose and would instead try to focus on specific use cases first for specific audiences (that would be willing to pay). In practice this would look more like an extended version of DDG's instant answers than a Google-alike, but I think the world is convinced that general purpose web search is a) necessary and b) the only valid approach to finding answers to questions.
Many search engines already exists for specific use cases:
- www.bailii.org for UK law related searches like court verdicts
- tachiyomi.org for searching manga
Etc. Generally speaking, search engines that cater for a specific use case are simply called "aggregators".
You will always find:
><Search Engine> is <bad/good> and the results are way <worse/better> than <Another search engine>.
><Search Engine> is only a frontend for <Parent search engine> <but/and> does(n't) do their own indexing.
>Results for <Topic (usually technical)> (in <country>)? on <search engine> are garbage. Search results for <purpose> are poor.
What you will see as a response:
>You should use <search engine> instead! It uses <different parent search> instead so the results are better!
>I agree, I didn't like <search engine> so I had to go back to Google.
What you won't see:
>Nowadays I only use <search engine> for some search, most of the time I use <specific source(s)>.
>Maybe you should use specific searches for specific purposes?
The two that you cited are very valid, and I'm sure many people use specific sources for specific things (most doing it unknowingly via apps). The main thing seems to be that (on especially desktop) the single purpose all-encompassing web portal seems to be the way to find something. The phrase "Google it" is a catch all for 'do your research'.
DDG also uses Yandex for web search (mostly Russian content).
I've used DDG near-excusively since 2013.