Currently on the coinmarketcap site only about 1590 projects compared to at times more than 1700 projects. They have left many projects without developers or scam projects. I personally invested in some of these projects and lost a lot of money like bitconect and centra. Do you trust the projects you are investing in and will keep them for a long time until they succeed or are they just looking for profit in the short term?
In reality, there are not so many projects explicitly being a scam and being founded solely for taking the investors' money and escaping. Most projects simply fail to 1) support their coin and 2) keep up with the roadmap and develop their products on time. Naturally, all this influences the price of tokens, so some of them are being delisted from cmc.