I disagree on your pov, when you disclude the top 10 coins all others combined are about 19% of the total mkt cap. The other coins in the top 10 have gained hugely on bitcoin over the last 2 years, just wondering if this will continue.
the trend is your friend, until it ends. altcoins are obviously correlated to bitcoin. at some point, both BTC/USD and alt/BTC charts will enter long term bearish cycles.
the supplies of the top altcoins completely distort things too. some of the most obvious examples of low usage/high circulating supply are right in the top 10. plus tether:
40,762,365,544 XRP
19,149,690,859 XLM
1,856,421,736 USDT