Bad things don't happen until they do...  I am sorry that this happened to you.  It sucks to lose money.  I think most of us have been there though.  Bitcoin is a learning experience and hopefully you've learned a lesson that will end up saving you more than $4,000 down the line.  My advice would be to use this as a learning experience and continue looking into what else you may not know about Bitcoin so that you can have more knowledge that will someday pay dividends to you.  I also wish you good luck in locating the receiver and maybe recovering the funds somehow.