Darknet markets present challenges in regard to legality. Bitcoins and other forms of cryptocurrency used in dark markets are not clearly or legally classified in almost all parts of the world. In the U.S., bitcoins are labelled as "virtual assets". This type of ambiguous classification puts pressure on law enforcement agencies around the world to adapt to the shifting drug trade of dark markets.[76]

Apart from BTC, the altcoin market is also experiencing similar colossal dumps. All top-ten altcoins are presently in the red as massive selloffs dominate the market. As at press time, Ethereum, the second-ranked cryptocurrency by market capitalization is struggling to stay above $180, falling more than 14 percent. XRP is also another casualty of the market selloff, falling by more than 12 percent.
The largest potential for ‘’disruption’’ to the current status quo lies in taking a chunk out of the payment processors market. Visa and MasterCard are estimated to take a 2 to 3 percent cut of every card transaction. By using bitcoin instead, merchants stand to improve their bottom line by at least 2 percent. In addition, because bitcoin transactions are irreversible, there is no possibility for chargebacks and fraud. This reduces the costs of operation by another several percentage points.

Trading bitcoin shares many similarities, but doing so through a forex broker is not required, and could be more costly if they charge higher fees than traditional bitcoin platforms like Coinbase. Investors should consider the risks associated with bitcoin and alternative currencies, and decide whether that form of speculation is right for their portfolios. (For more, see: The Risks Of Buying Bitcoin.)
Various journalists,[205][212] economists,[213][214] and the central bank of Estonia[215] have voiced concerns that bitcoin is a Ponzi scheme. In 2013, Eric Posner, a law professor at the University of Chicago, stated that "a real Ponzi scheme takes fraud; bitcoin, by contrast, seems more like a collective delusion."[216] A 2014 report by the World Bank concluded that bitcoin was not a deliberate Ponzi scheme.[217]:7 The Swiss Federal Council[218]:21 examined the concerns that bitcoin might be a pyramid scheme; it concluded that, "Since in the case of bitcoin the typical promises of profits are lacking, it cannot be assumed that bitcoin is a pyramid scheme." In July 2017, billionaire Howard Marks referred to bitcoin as a pyramid scheme.[219]

AVA Trade is a forex broker that offers bitcoin trading through a CFD. Two bitcoin CFDs are available, Bitcoin Mini and Bitcoin Weekly. The Bitcoin Weekly CFD has a 20 to 1 leverage and expires every Friday at 21:00 GMT. The Bitcoin Mini only has a 2 to 1 leverage but doesn’t expire. Both contracts are using data from BTC-E and AVA Trade adds around 10$ premium on top of the exchange spread. You can find more about the bitcoin trading conditions here. Here’s a snapshot of AvaTrade’s MT4.
In February 2014 the world's largest bitcoin exchange, Mt. Gox, declared bankruptcy. The company stated that it had lost nearly $473 million of their customers' bitcoins likely due to theft. This was equivalent to approximately 750,000 bitcoins, or about 7% of all the bitcoins in existence. The price of a bitcoin fell from a high of about $1,160 in December to under $400 in February.[67]

An initial coin offering (ICO) is a controversial means of raising funds for a new cryptocurrency venture. An ICO may be used by startups with the intention of avoiding regulation. However, securities regulators in many jurisdictions, including in the U.S., and Canada have indicated that if a coin or token is an "investment contract" (e.g., under the Howey test, i.e., an investment of money with a reasonable expectation of profit based significantly on the entrepreneurial or managerial efforts of others), it is a security and is subject to securities regulation. In an ICO campaign, a percentage of the cryptocurrency (usually in the form of "tokens") is sold to early backers of the project in exchange for legal tender or other cryptocurrencies, often bitcoin or ether.[47][48][49]

Bitcoin and other cryptocurrencies have been identified as economic bubbles by at least eight Nobel Memorial Prize in Economic Sciences laureates, including Robert Shiller,[192] Joseph Stiglitz,[193] and Richard Thaler.[194][13] Noted Keyensian economist Paul Krugman wrote in his New York Times column criticizing bitcoin, calling it a bubble and a fraud;[195] and professor Nouriel Roubini of New York University called bitcoin the "mother of all bubbles."[196] Central bankers, including former Federal Reserve Chairman Alan Greenspan,[197] investors such as Warren Buffett,[198][199] and George Soros[200] have stated similar views, as have business executives such as Jamie Dimon and Jack Ma.[201]
The receiver of the first bitcoin transaction was cypherpunk Hal Finney, who created the first reusable proof-of-work system (RPOW) in 2004.[22] Finney downloaded the bitcoin software on its release date, and on 12 January 2009 received ten bitcoins from Nakamoto.[23][24] Other early cypherpunk supporters were creators of bitcoin predecessors: Wei Dai, creator of b-money, and Nick Szabo, creator of bit gold.[25] In 2010, the first known commercial transaction using bitcoin occurred when programmer Laszlo Hanyecz bought two Papa John's pizzas for 10,000 bitcoin.[26]