Sometimes it helps to go granular and model something as an agent instead of system dynamics models. So this means that instead of modelling a stock-market as having a number of value versus growth investors, we can model each investor as someone who will buy or sell a stock based on some threshold.
The problem with modelling each investor as an agent is that we run into other problems.
Some investors will buy a stock when it goes up, making the stock go up even higher. This is an example whereby an agent produces positive feedback loops. Other investors will do the opposite and buy the stock when it goes down. This is an example whereby an agent produces negative feedback loops.
A system with primarily positive feedback would be like cryptocurrency markets when prices of bitcoin blew up or collapsed. If you really believe that the cryptocurrency markets will moon over the