Person B would profit more from his daily trading and he will be happy with that than holding his coin and do nothing about it.
The only factor for that Person B to lose is wrong execution "many" times.
And of course, hopefully the exchange site will not do some bullshit activity.
Of course that will be the only time he will lose profit if he is not patient enough to know what the chart is saying.
If the site starts to become shady then the person will really lose a lot.