1.  Alts have no value of their own

2.  The price of alts is a function of how much greed / fear is in the market.

3. Fear / greed is determined by Bitcoin price performance.  

4.  Alts are denominated in BTC.  

5.  When people are greedy they buy alts using BTC.

6.  When people are fearful they sell alts using BTC.