Because its founders Brin and Page have inborn genetic belief in a single Jewish God. It's the same force that led Einstein to search for Grand Unified Field Theory.
Gave a presentation to an analyst at DFJ. Showed her an alpha prototype. She said, very interesting, but we really wanted to fund <competition>. That other company was in a similar space, but did not have the product that we demoed. Then they got funded by DFJ and in 6 months, that company released an inferior clone of our demo. In 2-3 years they got acquihired by Google (the founders did not do very well judging from their subsequent LinkedIn jobs), and Google shut the product down. Our product grew bootsrapped and has been feeding us for 10 years, without making anybody rich, just comfortable.