Please read the following if you're dumb enough to sell, or you need to withdraw for emergencies:
Anything you sell that was held less than a year will be taxed at a much higher rate than if it was held longer than a year. That applies to the United States - not sure on capital gain taxes in other countries. Aside from trying to time the market, and complicating taxes with high transaction rates, all your lucky profits can be mostly eaten up by a higher tax rate. HODL.