We've got an Amazon Firestick, on to that we have loaded Prime and Netflix (both subscription, we have Prime as the OH buys shedloads from Amazon so it makes sense) and Showbox (free to download and use).The SVoD companies you mention are called FAANGs (Facebook, Amazon, AppleTV, Netflix and Google).
Whether they make “plenty of dosh” is very much open to question.
Netflix has never turned a profit. Whether the others have is moot as streaming service profits/losses are hidden in the accounts. As a group they lost a billion dollars in share price last November as analysts realised they can’t all win in the long term.
At the moment they are trying to buy/seize market share in a streaming land grab. Just under half of UK homes have a streaming service and it is doubtful if very many will ever have more than one, purely based on cost.