The Netherlands themselves were under military pressure by neighboring countries, Spain, and Britain, and was occupied and starved by Germany in WW2, and had many of their dikes broken.

Colonization is more an expression of prosperity, rather than its cause: to colonize, a country already has to be well developed and with a strong military and navy. Ask yourself: with Africa's resources and size, why didn't it colonize Europe, instead of the other way around?