alts market cap all depends on the last price that they were traded and thats the price for btc mainly as well. I think that if we don't see scaling problem solved this year that alts might get over 50% trading volume over btc.

The reason is fairly simple, people want money and they see that btc is a giant and they want to put their money and double it tripple it ... While they read about that there is some uncertainty about btc and while they see some alt pumpin they believe that it has value, that it maybe special. But intact they have done their lack of research and they are just buying.

To be honest I am sick of every other alt that is similar to btc nothing special. It would be much better to look to use them than just to pump them and turn money around. Money can't buy you happiness. But I also happen to know that btc and alts are just 70% speculation with an investors folding in the market. But much better is to be able to use them, I think that this is what btc have the most - usability over other alts.