The first money market mutual fund to break the buck was First Multifund for Daily Income (FMDI) in 1978, liquidating and restating NAV at 94 cents per share. An argument has been made that FMDI was not technically a money market fund as at the time of liquidation the average maturity of securities in its portfolio exceeded two years. However, prospective investors were informed that FMDI would invest "solely in Short-Term (30-90 days) MONEY MARKET obligations". Furthermore, the rule restricting which the maturities which money market funds are permitted to invest in, Rule 2a-7 of the Investment Company Act of 1940, was not promulgated until 1983. Prior to the adoption of this rule, a mutual fund had to do little other than present itself as a money market fund, which FMDI did. Seeking higher yield, FMDI had purchased increasingly longer maturity securities, and rising interest rates negatively impacted the value of its portfolio. In order to meet increasing redemptions, the fund was forced to sell a certificate of deposit at a 3% loss, triggering a restatement of its NAV and the first instance of a money market fund "breaking the buck".
All of those factors make mining cryptocurrencies an extremely competitive arms race that rewards early adopters. However, depending on where you live, profits made from mining can be subject to taxation and Money Transmitting regulations. In the US, the FinCEN has issued a guidance, according to which mining of cryptocurrencies and exchanging them for flat currencies may be considered money transmitting. This means that miners might need to comply with special laws and regulations dealing with this type of activities.
Basically, cryptocurrencies are entries about token in decentralized consensus-databases. They are called CRYPTOcurrencies because the consensus-keeping process is secured by strong cryptography. Cryptocurrencies are built on cryptography. They are not secured by people or by trust, but by math. It is more probable that an asteroid falls on your house than that a bitcoin address is compromised.
The Money Market enables the commercial banks to use their excess reserves in profitable investment. The main objective of the commercial banks is to earn income from its reserves as well as maintain liquidity to meet the uncertain cash demand of the depositors. In the money market, the excess reserves of the commercial banks are invested in near-money assets (e.g., short-term bills of exchange), which are easily converted into cash. Thus, commercial banks earn profits without sacrificing liquidity.