You can build a solution to any problem. But most problems aren't worth solving as a business. The trick is finding problems that are:
┌────────────────────────────────────────────────────┐
│ A problem worth solving has ALL of these: │
│ │
│ 1. Frequent — Happens regularly, not once │
│ 2. Painful — Costs time, money, or sanity │
│ 3. Funded — The sufferer has money to spend │
│ 4. Growing — More people hit this over time │
│ 5. Underserved — Current solutions are bad │
│ │
└────────────────────────────────────────────────────┘
Miss any one of these and you're in trouble.