During the time that I was pitching I flat out refused to do 5 year predictions, and my 1 year predictions came with a fair amount of bandwidth. Initially my partners thought I was crazy but in time we came to the conclusion that it is better to be honest and say that you can't predict further out than that rather than to make stuff up that can be shot down in no time at all.
And it did work, we did find 2 investors, one for 100K and another for 200K.
I'm not defending 5 year projections. Simply arguing for a different pitch method.
Projections are fine so long as the inputs are reasonable. If people don't buy your assumptions they won't buy your conclusions. 1 year, 5 year, or 10 year.
The problem here is that when you're pre-launch or just launched you do not know your product life-cycle yet, so it is absolutely impossible to get this right.
You can make a stab at it but until the first year is out there is going to be so much change to that projection that even if your input data was valid at the time you made the projection it will look like advanced science fiction by the time those 12 months roll by.
Fair. But you don't need to be accurate, just within reason.
Explaining your inputs logically is important for other people to see at your level. Plus as another posted mentioned, going through these motions helps you better understand your product and target audience.
And it did work, we did find 2 investors, one for 100K and another for 200K.