YouTube and AdSense are both extraordinarily profitable. Google Play and Cloud are great revenue drivers as well. Search Ads are still the king of the hill, but it's definitely not their only profitable project, and many of the "unprofitable" projects funnel traffic to profitable ones--Chrome gives Search uplift, Google Play can't exist without Android, etc.
Definitely, they found another cash printer in Youtube but to be fair, they bought that. My comment wasn’t intended to be definitive. Yes, a lot of their other products are really just funnels to their search ads though. Strategic plays have value too of course.
They bought YouTube well over a decade ago in order to jumpstart their position in streaming, once Google Video failed to take hold, and nowadays the original YouTube would be unrecognizable. It's not like they didn't have the chops to build it, or the business acumen to make it profitable; they just acqui-hired a competitor in the space.