It depends on their aim. If they want to use their btc right away, they have to convert them to usd to cover their expenses. Some wants to convert them just to get the highest possible amount they can get in those weeks and use it right away. We surely value it and thats why we convert it for us to use it because some doesnt accept bitcoin as payments. If you want to earn big, you invest your time into long term investment which is for many, is far too long which is bad for them cuz they cant pay their everyday expenses. e.i electricity bills, waterbills, foods and clothes etc.