Most small margin businesses I know of are ones which lease a warehouse or storefront location. They have a double rental expense between their residence and business location. This format usually exacts a heavy toll upon profit margins. In cases where rental costs rise, their profitability can disappear overnight.
Its much more affordable and profitable to run a business out of ones own residence or garage. While it may not be zoned for running a business. Benefits usually outweigh disadvantages.
In a worst case scenario, where the economy crashes and everyone regresses to a barter based system. Having some type of skill or trade is a better position to barter from than having a small business.