It is for their own security, if they don't want to disclose how much Bitcoin they are holding at then it is their choice and we cannot force them to tell it and they are not oblige to tell those information to us too, so I don't see anything wrong for that, whether they are lying or not, it doesn't matter at all, what we should matter is what we are holding on our own.
yes I experienced it ...
from the loss of money,, lost time, for almost 2 years the bitcoin market experienced a significant decline and certainly not only from the treaders who were affected ... from miners, investors and many others who were affected...
we can only hope for the best and hopefully there will be a good solution in 2020 that can raise the price of the bitcoin market up or at least stable and not go down like in previous years