It does sound stupid to us that know about that scamming technique and generally have experience, but many people are gullibl and not aware of all the dangers on the Internet.
I don't know, if you are into bitcoin and you even know how to transfer money online it means that you're supposed to know a couple of things about internet, no? I have friends who know zero about bitcoin and when they wanted to buy something I literally had to open the exchange account for them because they weren't absolutely able to do it alone. I just don't understand why someone should start talking with some random guy and before he "invests" the money and only later he checks on this forum.
Anyway I hope it wasn't a lot of money, it's a good lesson for the future, we all make mistakes at the end.