I can only imagine as it was thinking alian to me and before my time.
In times where care for human life was not important , it was a show of force. and attitude of we can do what we want. The British were the best a this.
Discovery of new lands brought the discovery of spices, fabrics and other valuables that could be traded without a care for the Indiginouse people.
Anything else?
A typical glossy version, Bodd.
It was the simple pursuit of wealth, power, and control.
There certainly might have been some supposedly benevolent motives, but these were really about power and control, e.g. supposedly religious domination, by Christian missionaries, but such attempts invariably introduce disease, or served to corrupt the base religion by merging it with local beliefs.
There were other purely racist motives, such as civilizing the indigenous, or educating the children of other "races", as typified in the Kipling's poem, The White Man's Burden. (Also codified in French as the civilising of other nations, mentioned by Durhamplumber, but I doubt he understood what it was)
For sure, there were some genuine intrepid explorers, but such missions were financed by those seeking the wealth that such missions would bring.
When people talk about the benefits that colonisation and imperialism has brought to other nations, such benefits were pure spin-offs of the real reasons for such colonisation. For example, railroads were built to ease the flow of resources, administrations were created to accumulate taxes, medical care was introduced to increase productivity, etc.
And this wealth created by the rich and famous in their raping and pillaging of other lands, was put to good use back home, to improve their status or increase their influence.