Why are some patented products not listed and sold by pyramid schemes?

There are many reasons why patents are underdeveloped. First, there is insufficient funds. Some patents need a lot of money from laboratory products to pilot tests to mass production. If there is no investor, it may be put on hold; Second, patents cannot be mass-produced, which is very common; Third, the market is immature. The purpose of developing patented products is to obtain benefits. If the market is immature, it may be put on hold temporarily. Fourth, the trading channels are not smooth, and the patent has not found a suitable transferee or investor.