In no world would Youtube be even remotely profitable without advertising. Google ran it as a $B+/year loss for years before managing to making it profitable.

Tell me now a believable alternative growth story for Youtube where Google didn't buy it and the service isn't "corporatized" and not losing money.

You can't compare an unprofitable small-scale startup product to what the same product needs to be to make it 1) planet-scale and 2) profitable.