Trading between btc/usd market isn't a big problem.
Everyone can do so.
It's just simple buy low and sell high.
Big deal is that when people see prices falling, they panic sell their coins to cut the losses.
This is a wrong approach, as when the prices fall we should buy more to get more profit.
Well people just be panic if they see the bitcoin price drop alot, no one cant refrain their selves to get more loss. Its a human nature imo, no matter how patient we are, except for economy experts or professional traders.