It's also much easier to follow bitcoin because, well, the whole market follows bitcoin. Bitcoin dictates where the market goes.
Not all the time, just like now, did alts followed Bitcoin? Alts just dump hard when BTC pumped.
It's really different for me to trade bitcoin and alts (especially when bull season). I do believe that when the price of bitcoin will become stable again, probably that the alts will follow also.
As you can see now, after how many hours/days when BTC pumps and alts dump and BTC still dumping, suddenly the alts are pumping (This kind of scenario I noticed on since last year)
This is where a smart trader takes advantage age, from what you said, you will see that both always go opposite direction which I agree with you, so Bitcoin and altcoins both have different season, we just need to learn how to adapt and take advantage of both seasons.
Probably we trade bitcoin during its own run and once BTC start its own bull run, we enter trades because that is when the market becomes much volatile and when Bitcoin is about to stop the bull run, then we should automatically know that it is time to trade altcoins. We have to study how to control the market and not the market always controlling us.