Kennedy half dollar rolls

Orlena

I noticed that the rolls of Kennedy half dollars (P,D) seems to sell out every year. Why is that? Are there many collectors of that series? Just curious

F117ASR

There are plenty of Kennedy Collectors. I don't recall them really selling out but I think a lot of buyers are ebay high volume sellers that sell uncirculated P&D mint sets. Some are also hunters of high quality examples (although you would be better off using mint sets for that).