I think the explanation is less about greed and more that ad-supported programming is almost always the only viable economic model. Cable worked brilliantly because everybody paid for a full range of channels, sure YOU only watched about 8 of them but other people had a totally different 8. Some channels survived many many years without earning any subscriber fees, just getting the distribution was enough and the ads paid the bills.

Anyone thinking that paid streaming subscriptions could entirely replace ad-supported for the long-term, never really thought it all through in my opinion.