I think this is closer to a 50B problem than a 1B problem. Not impossible, but I don’t know anyone who has 50B that they would want to spend fighting uphill to kill google.
Say, you manage to recruit the top-30 engineers who know all the in-and-outs of the google search engine. Add to that, their recent replacement of trad AI methods with full NN I believe, and I can't realistically believe it's not more than a 1B problem.
One of the reasons Google is going horizontal because their search engine can't be "magical" forever, this applies to their ad platform too.
* how many people worldwide keep their google places information up-to-date and not their local government office or their website.
* how advertisers can get value for their search ad campaigns; how to convince them of this
* how much google ad/targeting intelligence comes from off-site (eg Adsense, partner programs, xml ads)
* how many websites and website owners focus obsessively on their google presence making sure that even where Google’s tech gets it wrong they can get it corrected.
* how valuable the feedback loop is: google ads literally tells google what pages and terms are useful, what people like, and what to do more of at scale
* giving away free email and chat to build a whitelist of “good shares”
And that doesn’t cover video or the inverted index you need to provide governments access to emails and search terms. And so on.
These are largely not-software problems.
Hell they can even throw a spin on how it's about "privacy" and not about taking another way to bank on their walled garden monopoly and the Apple crowd here will gobble it up with "we are finally free from Google spying, praise Tim and his holy father Steve in heaven".
I've been arguing app stores are a monopoly for years now and the amount of cultist here that were like "Apple is doing it to protect me from bad software" and "I would not use my iPhone if there was an option to install a different store" was staggering.
Nobody else has this, and until they do, they won't be able to recreate Google.
You do NOT get added benefit from big data by taking it from millions to hundreds of billions. It becomes just a lesson in scale, without bringing any added benefit of insight.
Google is valued like "real estate", it's the best address. And then you need the advertising network for it be worthwhile.
Apple, like Microsoft, can replace google as the default search, but that alone is not a big chunk of the market. It might not be worthwhile.
Otherwise, of course it can be done, and for even less than that.