With big enough equity and proper risk management, one can do so. Problem lies with low equity & high expectation which often leads to improper risk management and a sudden margin call. i.e. it's really easy to make $1 with $1 billion account size with risk nearing zero, but trying to make $1 with $100 is exponentially hard & risky. These so called day traders opt in for later b/c they are trained by the course & society & influences to do so.