Where does Roku bring the extra $100M to buy unpopular shows? Why get Roku in the first place, most modern devices have an App that can stream any service
Roku is a very big player for the living room, greatly more so than Apple TV for comparisons. To be featured in Roku, they require you to support IAP which also means they get a part of those transactions. They also have their own ad platform that many partners/vendors use.
Why get Roku? It's easy to use and cheap, and in the US (believe it or not), it's what most people consume living room content on. I personally dislike the UX, but I understand its appeal which the numbers do not lie about.