Speculation is important to make profit but doesn't mean you should hold it for too long. Holding anything than Bitcoin for long time is just wasting time and money.
Whenever Bitcoin was pumping up during that 30% increase in 24 hours the other day, I looked at all the coins on coinmarketcap and they were all green. The reason for this is that you have to have Bitcoin to buy the other altcoins. Unless you're going through an exchange, depositing usd, and trading that usd for the coin you want, Bitcoin is required. This is why all of the coins are dependent on Bitcoins price. Real use case really has nothing to do with it.