Respectfully, I think you are definitely overestimating the cost of building a search engine. Do you have experience in search specifically? Asking in good faith here.

I think you're absolutely right that it's not trivial, but it isn't a completely unsolvable problem only addressable by the major spyware corporations like Facebook, Google, etc. I think you could build a decent search engine in about 6-18 months if all living expenses were paid and you could just lock yourself into your apartment with no distractions, with maybe a team of 1-3 other extremely talented engineers.