The answer is "Miriam ignored the market limitations."
A fatal flaw alludes to something that turned out badly in her business causing it to fail totally. Miriam opened up a store in light of her advantage and too few clients visited. Miriam ought to have directed statistical surveying to decide if there was enthusiasm for a yarn make store in her town. On the off chance that she would have directed the exploration, she may have acknowledged there wasn't a market for the item.