At this juncture, I want us to look at the potential risk by which this my friend has come to expose himself.
Or is there a smart move of him you can commend of him on that?
I believe there should be a limit to what we share with others especially if it has to do with investment, finance or anything related with our future plans. However, there are few exceptions in almost every rules and your friend might be aware of what he's doing. It wasn't just a random person but a childhood friend as said by your friend and you can't tell the level of trust in their friendship.
Moreover, he might probably be sharing this with him to win his interest into bitcoin investment as well. I know people can not be fully trusted irrespective of relationship between them but there are basically certain people you can not just keep something away from no matter how much you try to conceal it.