Investors should and do make their own estimates of market opportunity. Investors should and do demand help in making those estimates. A common way to help is

Investors should and do make their own estimates of market opportunity. Investors should and do demand help in making those estimates. A common way to help is to provide a full estimate plus the inputs you used to make that estimate. Now, I think a BETTER way to help is to provide ranges and discussions of the inputs, rather than point estimates. And it's rare that I've encountered an investor who didn't find that acceptable. But some version or other of the exercise is worthwhile.