Yeah your right its unpredictable but its depends of your strategy and what altcoin you choose..
In my opinion or tips i think better to always use coinmarketcap and choose top 20 altcoin or top 10 altcoin and choose them because those are legit altcoin that you can hold for a long time.
agreed, nobody knows what will happen when will it drops the price or increase the value. But like what you've said it depends on us how are we gonna do it, that's why some traders they used their premonition in trading. But updating the coinmarketcap I think it will help anyhow.
no doubt that it is difficult to predict about the price of bitcoin but in fact we can do that if we regularly keep eye on bitcoin, studying different sites, hearing news about bitcoin from different sites and using social media that can really help us about predicting the price of bitcoin. as currently we can see that people are predicting about bitcoin that the price of bitcoin is going to cross 1000$ in next week or even earlier that that.
Our prediction could not be right all the time but our effort will pay off once we work for it. Trading is not an easy job and a trader who's lazy will not gonna make his goal to be profitable, we have to work harder and smarter and that requires us to be more patient to spend time to learn from time to time.