I’ll point out a few flaws in your own opinion.
1. I’m not arguing about Apple building their search engine from scratch. I am saying Apple can build their own DDG replacement if they wanted to. If they did this, they will learn more about their users than ever before. Obviously there is the high risk that they build another Apple Maps and have to play catch-up.
If Apple would ever build their own search engine (either from scratch or by acquiring DuckDuckGo), it would definitely occupy a default position like they did with maps and Siri. That’s at odds with being paid by Google and I think that right now, they are not willing to give up billions of dollars a year, plus the resources it takes to develop and maintain their own search engine (not forgetting that they won’t be able to monetise it via ads the way google can).
What even would Apple with all this user data anyways?
2. The rhetoric to have Google pay more to be the search engine for Apple only helps with their revenue but makes their mission statement of being a privacy company hypocritical.
Apple can’t be held responsible for the privacy stances of other companies like facebook or google. Rather, Apple is helping by offering users the option of choosing service providers based on their privacy preferences. Such as the ability to choose DuckDuckGo as their default search option.
Likewise, Apple isn’t on some crusade to excise Google from its platform. Rather, it simply wants to encourage these companies to treat user data with more respect, the same way it is.
I am not seeing the hypocrisy here.
3. I doubt that Google considers DDG even remotely a threat. The DDG engine is crippled by itself without help from 3rd party engines. If Google did pay Apple more money, it’s because their budget allows it.
It did not stop Apple from replacing google maps with maps. That’s probably what Google doesn’t want to risk - antagonising Apple to the point where Apple decides that maybe they should just make their own search engine.