1. Throughout history, trade has been a necessary thing. They wanted to expand their trade in Africa, the Indian Ocean, and India.
2. Back then, there was no way of knowing the exact size of the earth. Maps were not the same, there was no GPS. The earth was bigger around than he had calculated.
3. I think, the Dutch failed to compete with the Portuguese and could not enforce a monopoly over the Spice Islands.
I hope this helps!
