Earlier quoted context omitted.
Even barring monetization aside, Popcorn Time is far from doing everything right. Have you tried watching a show/movie that isn't among the most popular? Chances are there wouldn't be enough seeders to get a decent experience.
I can only guess here, but availability of content must surely be one of it. In 2015, a brick and mortar store for renting physical videos still have content which online services do not, including some movies that was in the cinema over a year ago.
In 2005 or even 2010 I would absolutely have agreed with you. However in 2015 all those really great independent brick and mortar video rental places I used to go to anywhere near me are long since bankrupt and closed down.