My investment strategy is buying and holding. I feel that day trading is time consuming and stressful as well. I agree that some coins prices fall after ICO but not all projects. That is why we have to research carefully before investing. Solid projects are still worth investing in.
I think this is the most common technique people are doing now. As the price of bitcoin and some altcoins as well are steadily gaining, many have chosen to buy and hold on to them for future profit. However, that move can sometimes be bad for the market, since the demand goes up, but the supply is put on a stand still because no one is getting rid of their coins. So, the smaller market players are not getting any movement that unfortunately kills most of them out, if not, loses their traction and potential.