I think that many Altcoins are shitcoins (sorry about my French) and many people, including me, are speculating on them - as a result of this - as soon as an Altcoin I has made some nice proffit +50% or 500% I sell it and buy bitcoins and so do many other people, that makes the price very volatile.
in order to have a sustainable price moovment up we would need to see a real life implementation of the Altcoin and for today we have no real implementation of 99.9% of the Altcoins
...only promises and projects that are in the future