As a consumer, I trust valve more than Google to make decisions that are better for me. They could be doing a lot more to squeeze money out of me, but they won't do that. My stuff feels safe on steam even if it's under DRM.

I normally don't buy movies, but I might buy one in a sale. In fact, I don't actually know of any services that sell / stream them outside netflix (they exist, I'm sure). If valve can convince the movie industry to play by steam's rules, they can make money. Plus movies get access to advertising on the steam platform.