Can anyone actually make an estimate with any reasonable degree of accuracy if the sum they need to estimate is in the trillions of dollars? For example, it se

Can anyone actually make an estimate with any reasonable degree of accuracy if the sum they need to estimate is in the trillions of dollars? For example, it seems that in research usually when people say that something is a decade away what they really mean is that they have no idea. Is there a good reason why that is not the case here and the 1.5 trillion would be well spent?