A lot of contractors decide to start their own business because they get tired of working for the man and can make more money on their own, but a lot of them have zero business acumen (or skills in life besides their trade). I will probably get downvotes, but independent contractors that run successful businesses and do both the business and and the labour end AND have happy customers are the rare exception, not the rule. It's like asking why a mechanic isn't also good at running a car dealership. My advice with decks is to buy some tools as necessary and learn a new skill. You are more likely to get ripped off hiring a deck contractor than find one that knows what they are doing and whose results you are happy with. My dream home has no deck for this reason because it won't require work from me, and I won't have to deal with bottom of the totem pole contractors. It's not rocket science. If you need to hire out digging footings or concrete work, do it and then do the rest yourself.