As an average person we will always think of making good profits from any investment and we hope for the same from bitcoins too and that is only possible if you hold your bitcoins for a long term as day trading is very risky and you don't want to loose your money by making a wrong move so long term holding is better.
But i think that even there are so many people who are earnign a good money from short term investment. Actually it is depending on the interest of the people that either they are interested in short term investmet or long term invest, In short term investment one need to remin more active and msut have a very good experince only then it is possible for hime to make money from short term investmet.