IOTA price is falling because of the way they initially distributed the tokens. Every IOTA that will ever exist was created in the first transaction. Those IOTA then spread out from there to more people. The problem is that its not spreading very much. Years after its creation 82% of all IOTA is still held by only a handful of wallets.
Once IOTA hit the markets it became easy to sell these tokens and cash out. This is inherently inflationary, meaning a huge increase in circulating money decreases the value of each unit of that money. Huge sums of IOTA are being dumped onto the markets as the original whales cash out on their 1.5 bil market cap. This will continue for quite some time until the gigantic original accounts have been emptied. I have no idea where it will bottom out, but if bytecoin or dogecoin is any indication, I would guess sub-penny levels.
In theory this process will not change the market cap. The same amount of dollars are still in the market so it does not matter how many tokens are floating around. In practice everyone will see the value of their tokens plummeting and panic sell immediately. This process will remove money from the market and lower the market cap.
Its a little bit like money printing on a massive scale. Like when Wiemar Germany decided to print out quadrillions of additional marks to cover their debts. The flood of additional notes caused the value to drop so dramatically they eventually were worth less than the paper they were printed on.