Yes, in my opinion it is very profitable to trade altcoins. I don't have one coin in mind. Very many coins can grow, the most important thing is to have time to buy a coin and sell it at the right time.
Thank you Mr. obvious and how do you know when is the best time to sell and the best time to buy if you don't have coin to hold like you said earlier 
Trading without enough knowledge about this business is a 100% loss and failure. You must weigh all pros and cons of this activity, find out if trading is for you, and then try doing it.
Knowledge isn't the only factor to worry about. You may have probably seen that lucky guy would make lot of money than you, if you don't have luck then it's useless either.