1) It provides quick cash so it removes the stress of having to look for money too soon.
2) Direct customer feedback while working with them on day to day problems. At this point you really want to understand your customers pains so later you can solve them with technology.
3) Initial validation/traction for your product. At the beginning, customers will value your consulting way more than your product, but for every new customer, try to provide less consulting and cover the rest with your product. Check if your customers are equally happy.