"Why exchange regulation is appropriate

The SEC has argued before that the cryptocurrency coins and tokens sold in initial coin offerings closely resemble securities, sharing many of the same characteristics as corporate stock and other business interests. Most people invest in ICOs in the hope of seeing the value of their investment go up, and creators of crypto-assets often offer them to the public at large to maximize their potential distribution and popularity.

By that argument, if cryptocurrencies are securities, then the companies that specialize in buying and selling cryptocurrencies are subject to regulatory requirements governing securities exchanges. That requires either registering with the SEC or qualifying for an exemption from the registration requirements. By imposing those restrictions, the SEC seeks to protect investors and prevent fraud and trade manipulation from occurring."

https://www.fool.com/investing/2018/03/11/sec-to-bitcoin-investors-you-should-demand-regulat.aspx