Not all coins are bad to hold, it depends on what coins you hold. I would like to suggest Ethereum and bitcoin they are profitable for holding on long term basis.
that's a rather stable strategy, not the most profitable but not so risky as well. Although for risk-lovers a holy grail is a bunch of just post-ICO altcoins. TRON is a good example that holding shitcoins may be very profitable, but you need to spot some obvious features of ICO/token. In case of TRON Bitmain connection was one of the major indications of possible pumps in the feature.
So basically, if you have free time to research small cap tokens - great, if not - just buy stable cryptos like BTC or ETH. That;s my advice.