You are comparing subjective predictions and mathematically modeled predictions. They are not the same thing. We have enormous amounts of mathematical modelli

You are comparing subjective predictions and mathematically modeled predictions. They are not the same thing. We have enormous amounts of mathematical modelling and a vast history of information about our atmospheric history. Using this, we can make inferences about what is likely to happen due to climate change. If I were to just make a rando statement about what will happen when climate change comes, that's different. Learning to separate the two is an important tool.