There are always new ICOs, IEOs, but over time, it turns out to become more difficult for new ICOs, and IEOs successfully raise funds they plan. The fact is, investors, from their past investments and their losses, actually become more careful with their investment decisions. They don't naively believe in investment advice from their friends, group leaders, etc. They changed themselves, and spend more time to read, learn, and investigate projects that they have interests and consider to invest.
Therefore, scam ICOs, IEOs mostly failed, but I don't think that they are reasons as you mentioned.
Personally, I saw growths of Bitcoin and Ethereum, in their liquidities.