Bitcoin's market share has fallen below 35% after treading above 55% for most of 2017, and the total market cap of all cryptocurrencies has surged past $750b. While crypto pundits have provided a wide variety of explanations, many cite bitcoin's slow transaction speed and relatively high (mining) fees - issues that speak to persistent scalability issues for blockchain.
Bitcoin alternatives are closing the gap with the market leader after names like stellar and cardano became red hot as 2017 was closing. The biggest cryptocurrency’s share of market value has fallen to a record 36 percent from 56 percent a month ago, according to CoinMarketCap prices for coins and tokens. Stellar, designed for cross-border payments, has more than doubled in the first trading days of this year, achieving a record market cap of more than $13 billion. That kind of move raises questions as to whether speculators will drive up second-tier digital coins at the expense of bitcoin, even though they have different purposes. The paper value of all cryptocurrencies combined has more than doubled to almost $700 billion in the past month.
http://fortune.com/2018/01/03/bitcoin-altcoin-litecoin-ethereum-ripple/