When Splinterlands had that first 10X influx of players a lot of the whales rented swaths of cheap rentals and then listed their collection at much higher rentals. It caused a massive rental price increase, and was pretty easy to do for those holding large collections of cards and I think the rental market has not yet recovered from this (and maybe never will). If I was a dev I would put limits on renting cards if you already have it in your collection and even rental price caps at a certain percent so people can't just horde cards and rent for unfair price gauges. It severely undercuts how new players can advance.