no one knows what altcoins will look like in the future which is clear at this time it is very difficult for us to get profit with altcoins, so I am amazed that it is better to hold top coins for example btc and eth which have clear movements. 
I agree with you, it is better to hold top altcoins in the market in which we can gain profit. I learned my lesson since I hold too many altcoins in my wallet which is not profitable. Better invest those top coins that we can earn profit even market will down it will rise again. So my top asset in my wallet is btc and eth, yet I'm also adding top alts to hold.