That's a good question actually, they could have gone with a similar strategy as Apple did (gifting months to people to use their hardware, either camaras, consoles or tv/phones) and they actually have a decent amount of self-produced movies and co-produced tv shows like Breaking Bad. The reality tho is that Sony as a whole doesn't have that much income itself at the movie/tv department as they are where they are because of their gaming department. They could invest on a streaming platform but the income for all of those services is not a safe bet (as netflix has been losing money since the start practically).

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tldr; too much investment for an insecure market