I will try a whack at this question.
Although Ceres has a large quantity of water, it is NOT unlimited, and distances between asteroids are HUGE. It makes much more sense to seek out water sources closer to your hard rock mining operation than take up to a year or more making the round trip just to pay Ceres prices for water.
I would think that water mining would become a viable entry level activity for a 'Mom and Pop' operation just getting started in the belt, what with not only water being extracted, but all the volatile chemicals that are likely trapped in the ice of a dead comet or other water rich chunk of rock.
Say a family group arrives on Ceres, Mom, Dad, Preteen Daughter, Dad's Brother, his Wife and Pretween Son. Unless they come with an appreciable stock of trade-able metals and goods, their prospects don't look good, do they?
They are ambitious however.
Dad and Mom land jobs on the docking bays manhandling maglev containers, while taking classes to get their tug pilot certificates from one of the bonded training centers, then take jobs as Tug Jockeys .
Uncle is a stay at home parent that does accounting over the tanglenet, while taking classes in astronavigation. Aunt takes classes in repair and building spaceships (small) and gets a job at one of the shipyards.
After about 3-5 years, Mom has her Ship's Master Certificate (Tug) in hand, Dad is up for certification as a Master Pilot, and Aunt has an Engineer's Certification , so the family turns its attention to the next step: Ice Mining.
They have saved up enough to Lease To Own a small tug with attached ice mining and refining platform for one year. They need to stock a year and half worth of consumables, fuel for a year long journey, power module for the platform's initial month of operation, by that time fuel wont be a problem, 3-5 hauling bladders, and a medium sized nano fabricator for replacement parts and organics. Also FULL Insurance on EVERYTHING AND EVERYBODY!
So the family goes to Tony's Tavern, Space Tug Rental, and Loan.
Uncle handles the negations, and the family agrees to a 5 year loan on the supplies and insurance premium.
Tony will sell shares in the loan to investors to lessen his finical burden in case of default, naturally.
So the family sets out to maybe not strike it rich, but willing to give it a try.