There are infrastructure costs (cable, fiber) and content costs. It was never clear to me why splitting the costs across multiple companies should be inherently cheaper than getting it all from one place. However, streaming does give you way more options than the typical local cable company, and it is completely possible to watch for free if you're willing to watch lots of commercials.
By the way, an article I read recently said that most streaming companies are losing money.
Banned but back. Because why not?