If you have to convince VCs about market size for early stage investment (seed, A), you likely are talking to the wrong people. VCs who will fund you already a

If you have to convince VCs about market size for early stage investment (seed, A), you likely are talking to the wrong people. VCs who will fund you already agree there's a potential market and are willing to make a speculative bet based on patterns like data + open source that have worked in other investments. Market numbers tend to be more or less imaginary at this point.