I miss when Amazon prime would refund you the remainder of the month when you cancelled.... I have no interest in being a prime member and actively avoid buying anything from Amazon. But sometimes I need something I can't find locally ASAP and giving them a quarter or two to have prime for a day was a solid option.
Paying $15 a month for "free" shipping which is also included in the price point of the products sounds like a stupid practice too. Lots of people doing it though.
If you buy enough, that fee is worth it or you will pay a lot more in shipping. Those of us in small towns without a lot of options benefit from Prime. Amazon is an evil company, but it's them or another big box store owned by another awful corporation for me. At least Amazon is convenient.
I'm in that boat. I buy enough where getting prime is worth it. I also use their prime video and Amazon photo services so I'm definitely getting my money's worth.