It’s hard to pinpoint one reason why cryptocurrencies have increased so much. I’d say there are five reasons that have probably driven demand:
Increased Awareness of Cryptocurrency: Many people who 6 months ago haven’t heard of Bitcoin or Ethereum are starting to hear about. They are especially interested because they see articles such as, “If you bought $100 of bitcoin 7 years ago, you'd be sitting on $75 million now.” Lots of people are looking at this as an opportunity to make a lot of money quickly.
Demand from Asian Markets: Countries like South Korea and Japan are extremely interested in the cryptocurrency market. It’s citizens see FinTech as the future of finance and cryptocurrency is leading that revolution. They are especially interested in digital currencies like Ripple and Stellar because of the impact it will have on their banking system. China has also begun to have more broad acceptance of cryptocurrencies and the 3 big crypto exchanges have announced expansion to other tokens other than Bitcoin.
An increase in token sales: Coindesk reports through June 9th that token sales have raised $327MM not including the recent Bancor sale which raised ~$150MM. This also props up Ethereum because most tokens are built on the Ethereum blockchain and take Ethereum as their primary means of payment. This is artificially reducing supply and thus driving up the price of Ethereum as many companies aren’t selling there Ethereum. Many people think that because they are new coins, they will replicate the returns that Ethereum and Bitcoin have produced, but the reality is 90% will probably be worthless in 3 years.
Acceptance of Cryptocurrency by Major Governments: Governments such as Singapore and Russia are exploring national cryptocurrencies. This is a huge boon as more and more countries are taking a smart regulatory approach to cryptocurrency. Japan legalized Bitcoin as a method of payment.
More enterprise adoption: The Enterprise Ethereum Alliance (EEA) added 86 new members in May many of which are Fortune 500 companies. Companies like Toyota, Accenture, and JP Morgan are building blockchain using Ethereum.