I somehow agree with your statement but we should always pick top10-20 coins from coinmarketcap. Holding Bitcoin, Ethereum, Neo, Dash and Litecoin can be worth off in long-term. Like as you I also hold some coins that was really at good price 2-3 months back but now it has been reversed if I sold that time so now I can buy more at less price. But we can not predict perfectly. Always hold the trust worthy coins.