Money flows into and out of the crypto currency space have been as cyclic as the Wall Street stock market.
Large moves in coin price to the upside happened in May / June 2017 followed by a downward move in the June / July time period. With some uncertainty in sentiment among crypto miners and traders, volitity rules the day. Overall, the trend lately has been to the downside. Several factors play into this.
Market uncertainty of the effects of the BIP-148 / SegWit implementation sometime between August 1st, 2017 and November 15th, 2017 saw some individuals diversifying their holdings or cashing out holdings to fiat currency opting to put some in mainstream brick and mortar banks to be safe from an crypto-economic storm which may occur around this User Activated Soft Fork (UASF).
You can read the exact software specificatiion at https://github.com/bitcoin/bips/blob/master/bip-0148.mediawiki
The Previous Thirty-Day Volume in USD:
Rank Coin Name 30-Day Volume
1 Bitcoin $36,738,094,336
2 Ethereum $31,631,986,336
3 Litecoin $14,823,662,832
4 Ethereum Cl. $4,913,296,584
5 Ripple $4,726,928,232