If most people are treating crypto currencies as an investment, will it effect the long term price just decline? Is there any statistic in terms of how many people holding bitcoins (and Altcoins) for long term investments and how many are actually using it spend? It would be good to have this clarified.
No, if people continue to hold their currency and demand stays the same or increases the long-term price will increase.
As far as statistics, the most reliable set are from the charts at
Blockchain.info.
Alternative currencies can't really be spent anywhere. For example, who accepts Ripple or Dash for payment of goods and services?
And as for Bitcoin, its acceptance as currency isn't widespread or consistent around the globe. And the fact that transaction fees have increased and confirmations are taking hours it's become less attractive for retailers to adopt as a currency for payment. This tends to have the benefit of keeping prices up, but it also requires that demand remain stable at least.
This last week we've seen a sell off and that's because people are selling their Bitcoin (and other cryptocurrencies). I believe it's due to fear related to the Aug. 1st Segwit activation, but that's just speculation on my part.