Do you have any credible source indicating that "billions will die"?

what I stated was "I wouldn't be surprised even billions die.", that implies that it's my understanding and opinion and I do not need to link a source for my own opinion.

If I stated that "I think everything will be completely fine", I would expect people to challenge me on that to provide some kind of evidence. Hyperbolic statements on both sides of the argument are not constructive.

You've mistaken a statement for an argument