you can't compare a traveling salesman with samples and sells out of a catalog or contracts with someone hauling around equipment trying to make a living off of the actual product in their RV, can you? how do the antiques people do it? they're selling higher dollar merchandise and are on a consistent circuit, hitting their target market. just taking stabs at fairs, festivals, events, etc., and you're not necessarily hitting your market (he said it was an adventure brand. you might as well be selling horror tees next to grandma peddling her home crocheted doll clothes. and this indicates potential sales of 100 shirts per day to you? hmmm, not to me, it doesn't, not by a long shot. look, if you're not selling to your market, you're going on a fool's venture, it's as simple as that.)
yeah, johnny cupcakes inspires a lot of people. and a lot of people forget that gas was half the price of what it is now. they also forget that he had an awesome design and tons of people who wanted that design based on the fact that he was in a band that toured nationwide, so thousands of people saw the product for hours on end. all most people take out of that story is that he sold shirts out of the trunk of his car, ne'erminding the supporting evidence that made him a success.
as far as attending conventions and setting up there, again, it's no comparison. in fact, that's a ludicrous comparison. these companies don't support themselves selling just to people at a show. if they did, they'd be out of business. they traipse about *demonstrating* their product, much of which requires financing. often they sell their products/equipment at a discount at the end of their run just to get rid of it as not to have to haul it back as it's now used.
of course, you're probably referring to ppl that sell shirts at a show. sure, they'll bring their stuff. again, though, it's apples and oranges. you're comparing a more-or-less set circuit of events with a market that's more likely to buy with hitting whatever place you can scrounge up along the way that has nothing to do with your product whatsoever. too, the OP makes it sounds as if this is an extended venture, whereas those attending events take breaks, skip a show here and there, and it's sometimes a seasonal thing anyway. i have salesguys i only hear from at certain times of the year ~ when it's appropriate for them to do so.
selling 100 shirts per day is a heckuva goal! what happens when you're rained out? bad sales because you're stuck on the fringes where people are too tired to walk to by that point? or just simply no one buys because your product doesn't fit in with the sauerkraut festival crowd?
can you find exceptions? sure, you can find exceptions to anything, but it doesn't prove anything other than something is conceivably possible *if*.... that's my point, there are a lot of 'ifs' here that's not adding up to a successful outing, imo. just hitting the road with a product, regardless of whether or not you're able to actually produce it, with no plan whatsoever would be calamitous to 99% of the attemptees.
i mean, what fool *wouldn't* try setting up at local events, the kind he plans to travel to in a second-rate gas-guzzler, first before doing this to see even if he could sell ten shirts? this may be going out on a limb, but i'm betting those provided examples knew they could sell their product before heading out on the highway. in other words, they had a plan, not a whimsical adventure scheme, a dream, and some hope. i also view examples like that with a jaundiced eye, as there's invariably a lot of the story that's being left out... usually by the people telling the story, usually to make themselves sound more adventurous than the truth of the thing, lol.
without knowing if whether or not you can even move enough product to support yourself while on the road by trying it locally first, this is just a bad idea. others do it because they have a plan and years of experience with a proven product.