Not really, there's a very particular type of fallacy that is people sticking small seeming percentages on markets and then suggesting that that percentage is a

Not really, there's a very particular type of fallacy that is people sticking small seeming percentages on markets and then suggesting that that percentage is achievable profit. Unless you go completely viral it's going to be one sale at a time with no percentages in sight. Percentages would occasionally be an acceptable form of measurement when there is significant market research regarding a highly targetted group. A good way to work out if the members of that group would buy stickers is to ask 100 of them at random and see how the answers went. Then assume that a good portion of those were just saying yes and will not follow through. There's a significant benefit to saying yes in that you are more likely to gain the option of buying a sticker without necessarily having to buy one.