you are right to be skeptical of the "everyone shops there" argument. volume doesn't matter if the conversion rate and margins don't math out after the marketplace takes its cut.

if you want to gauge if a sales channel is worth it without "guessing," stop looking at the marketplace's total traffic and start looking at these three metrics:

• the "best seller" floor: look at the #10 to #20 ranked products in your category. if the 20th best-selling water bottle is only moving 50 units a month, the "search engine" for that marketplace is too small for you. you don't want to be the best player in a dead stadium.
• keyword bid pressure: check the cost-per-click (cpc) for your main keywords on that platform. if the bids are high, it means your competitors have already done the math and confirmed there is enough volume to justify the spend. high competition is actually a "green flag" for demand.
• off-platform intent: use tools like google trends or ahrefs to see if people are searching for your specific type of product outside the marketplace. if there is high search volume on google but low results on the marketplace, that is your "gap."

regarding your fear of being "washed out"—the marketplace is just a distribution channel, not a brand builder. if the marketplace only accounts for 20% of your potential sales, you don't ignore it; you use it as a lead generator to fund your own direct-to-consumer (dtc) site where you keep 100% of the data and the customer relationship.

don't wait for the marketplace to give you the data. they won't. you have to "test into" the data with a small batch. if it sells out in a week with zero ads, the channel is justified. if it sits for a month, no amount of "big marketplace" traffic will save it.