I even witnessed a company who started with a product and then went down the road of customization, 15 years later arriving to a point where they are a custom d

I even witnessed a company who started with a product and then went down the road of customization, 15 years later arriving to a point where they are a custom development shop using all the same product simply as form of advertisement (proof that they are competent). Just by continuously taking the offers of enterprise clients to customize their product to their needs - it quickly turned out that it made a lot more money than selling the product. Then, these clients started to hire them to do unrelated things, and recommend to other clients to do unrelated things as well. Their last license sold was about 5 years ago. But probably making more money than they ever planned to make with the product (the product was planned as a lifestyle business, not a startup - say they never tried to look for any funding).