I'm going to call my friend dumb
Why do you think you friend is dumb?
He's now broke because he made stupid investment.
It's understandable that your friend wasn't thinking his best, but you don't have to put him down for it. You need to care for him and cheer him up instead of kicking him while he's down and making him feel worse.
I'm going to tell him what I think, I bet this will make his depression worse.
If you are a true friend you need to help them out. Would you want others to degrade you because of your mishaps? Try to soothe their discomfort and it could improve your relationship and bond.