It's ok, you're probably not the market for vegas casinos either.
I'll use Amazon to rent movies now and again. When there's a new season of something like "The Man in the High Castle" or complete seasons of other stuff I like become available then I'll pay for just a month to watch these then cancel the sub again.
I also find it slightly annoying when Prime deliveries go from "Next day" to "Two days" randomly, especially around holiday seasons. I queried this with them giving examples of SKU's that two days before were available Next Day and then suddenly change to Two Day delivery despite being in stock, but it's like talking to a brick wall.
Perhaps in the US it's a different story where due to licensing there's a much larger selection of content available, but the UK Prime is a bit meagre.
It looks to me like they went with something very similar to the 24h gym model - all these benefits which you don't end up using.