Many things in the world can’t be proven and many problems can’t be solved. Sometimes that makes our irrational human brains not even try to solve the problem or come up with zany numbers to try to make things work. Figuring out the scale of a problem or situation is hard but the most important part of predicting where things will go. A 2 fold increase is very different than a 20% increase.
I think many times the mere idea of looking at the numbers that are available to us is overwhelming and scary. I tend to round down in my projections because I feel it is safer to do so. But that also means that I could miss out on opportunities because I underestimate their value. There is no solution to the problem, but the only way to improve is to look at the numbers you can, make your evaluations based upon them, and keep gathering information.