Obviously the 1% argument is completely invalid. However, knowing the size of your market is always important, and looking at the percentage of that market you

Obviously the 1% argument is completely invalid. However, knowing the size of your market is always important, and looking at the percentage of that market you need for success, can be a good checkpoint. For example, imagine that you need to bring in 100K to break even with your product. Say you look at the market you're trying to enter, and find that selling 100K worth of your product means that you need to sell to 5%, 10%, or say 20% of the market, then maybe you should reevaluate the product. On the other hand, if your break even point is selling to "only" 1%, or .5%, or .1%, then at least you're aiming for a realistic market. By no means is anything guaranteed, but it can give you an idea if you've got a shot.