Just weighing in as a reformed Marvel fan and lifelong Star Wars fan: I started keeping local copies of that shit almost a decade ago and recommend to anyone I know to do the same. You never know when a streaming company might decide that it is no longer worth the bandwidth to host it, or if the rights will be transferred to a new service that I won't already have (i.e. all ot them). If you genuinely enjoy almost any media in the modern era you need to have a local copy, because if you don't some corporate entity may just decide to make it lost media on a whim because it becomes only moderately profitable.