It's profitable, yes, but the difficult part is that you need to know when the coin is bumped or dumped. You can't know the future so that you can surely know that you can earn profit or not
There is anther way for the difficult part. If you can get some secret information before it go to public,such as one alt-coin will hit on some big exchanges, and buy this coins immediately, then you can get a quick profit when it happens.