However, there were a lot more political reasons. Firstly, having an industrialized country, military strength and a large population alone did not grant “Great Power” status anymore and hence colonies had become a prerequisite. This was especially true for the nascent states of Italy and Germany who were seeking recognition and a 'place in the sun'. France, too, wanted colonies in order to lessen the humiliation of the loss of Alsace-Lorraine and to make France the Great Power it once was.
In some countries such as Germany, imperialism was carried out in order to distract the public from local problems by showing them a 'glorious' empire abroad involving colonies; that was the aim of Kaiser Wilhelm II.
With the improvement of media such as newspapers, public opinion also became a factor in imperialism. For example, as a result of the British public's outrage at the Kruger Telegram, Britain went on to wage war against the Boers in South Africa.
As there were many rivalries in Europe, they were bound to spread in Africa and Asia as a war of prestige. This can be noted by the fact that when Britain began claiming lands in the various parts of Africa, other countries such as France and Germany also followed suit starting a race for imperial power.
Britain acquired colonies in Australia and New Zealand, not just for economic purposes, but also for exporting their population to. France acquired Algeria for the same reason.
There were a few other reasons for the rise of imperialism that were neither political nor economic though.
For example, the White race claimed that it was superior to the other races and wanted to spread civilization to the 'savages' in Africa. Christian missionaries went to spread Christianity in Africa where they thought the Africans were following pagan rites. These missionaries helped the Europeans indirectly by creating pockets of local support.
Small pressure groups consisting mainly of travelers, explorers, intellectuals and businessmen such as Cecil Rhodes, de Brazza and Karl Peters wanted colonies established for their own motives.
Since China and Africa, with the exception of Algeria, Libya, Rhodesia and Kenya, were mainly not suitable for emigration of population, financial investments were made there. These had to be secured due to which political control was often taken. From this, it can be seen that although Europeans started out colonization as an economic venture, they had plans for political control. Another reason to believe this is that political control was not required to extract raw materials.
Strategic bases were also made such as Britain's control of Cape Town and Egypt so that India was more accessible.
Therefore, I think that although economic reasons 'seem to be in the foreground, more important were the political reasons in the background.
