Serving for a multitude of purposes and being renowned for their efficiency and reliability, spreadsheet solutions have a major contribution to business management and development. Existing spreadsheet solutions are no longer limited to accountancy processes (monitoring financial data, managing budgets and facilitating a series of data manipulation processes); they can also be successfully used as means of business analysis, organization, as well as forecasting, allowing companies to gradually expand, achieve better exposure and neutralize the competition.
You can build a reputation as an expert spreadsheet developer. This certainly doesn't hurt the resume. Using Excelville.com to sell spreadsheets allows you to set up a profile with your work, biography, and other info that certainly makes for good conversation material during interviews.
Not dynamic : Data ranges become redundant when new records are added, resulting in established formulae needing to be altered. Overlooking these errors can be embarrassing and downright expensive, especially if important decisions are being made based on the data.
You could make money doing something you love (or like [or maybe not so much but just really good at]). It's great to see a spreadsheet come together, and usually a lot better than what you originally envisioned. Especially when the dang thing works.