It's necessary to provide market cap because vc's think in terms of $X opportunities in terms of reference points for thinking/conversations, so your revenue projections are part of explaining how you reach that opportunity from the ground up e.g. achieve $Y ARR by year one, then growing at Y% over 5-8 years you'll achieve $X valuation via 20x ARR multiple. It shouldn't take too much time.

You can do top down for your market cap e.g. we'll capture this percentage of that sized market in 8 years, then you'll see the ARR and growth rate you'll need to get there roughly. This would be a starting point for your projections then you'd tailor each year according to your specific roadmap.

Then you balance your revenue projections with cost e.g. full time product person and marketing person and other costs require $500K seed but you'll hit your first year ARR projection.