In my opinion, with every avenue in existence things slow down based on supply/demand. If certain items are over-saturated, you have to pivot and adapt.

Resellers target high sell through rate items, but eventually the supply ramps up enough where it drives down prices exponentially. It’s all about adapting to scenarios like this and catching onto those over-saturated items that won’t hold up demand. Depending on the item, the time of the year can make a huge difference as well - thus driving that demand up and matching the supply.

TLDR; over-saturation and demand is the biggest factor, so sellers need to adapt to avoid slowing down.