Google's a publicly traded company which is profitable in other areas. Search can carry the load financially while they achieve market dominance in other areas.

This model is based on removing public market forces on a company while the company bleeds money in order to achieve dominance.

W/R/T other SaaS companies doing the same, SaaS startups exit strategies include acquisition that D2C business don't really have. Who's going to be big enough or see enough value in buying Uber/WeWork/Doordash to augment their current offerings? Amazon can't buy them all at the peak of their valuation.