I think not only newbies made mistakes about you've mentioned above but also the users in higher ranks. Even though they are in higher ranks but still they made mistakes. But as you shared this kind of idea well maybe it can be prevented by all users in bitcoin. And it only depends to the users if they want to made that things even they already know what's the result of it
Indeed, most of the high rank here in forum made a huge mistake before. One mistake that all users of bitcoin can made is not saving more bitcoin before because as of now bitcoin price is pumping up, its value is increased more than ever before. As the demand increase at the popularity of bitcoin develops more thing about bitcoin. So if people save more than before it pump more people earn more. But if I am one of them that did not take the risk.