Who benefited the most from imperialism?

Imperial
nations benefited from imperialism, which is why it happened in the first place. They benefited
for a number of reasons. First, colonies provided outlets for manufactured goods. This happened
at a time when many feared that the efficiency of new technologies might lead to surpluses which
could have crippled economies. This was disputed at the time and since, but it is certain that
the owners of major manufacturers benefited by having captive markets for their
goods. 

Colonies also provided cheap raw materials. Big companies bought up
large swaths of land in places like Africa and Latin America for mines, timber, and agriculture.
These were acquired more cheaply, and under better terms, than they could have been
domestically. In Latin America, for example, American businessmen owned vast sugar and fruit
plantations. When these holdings were threatened by political instability, they turned to the
United States government, who often supported them through military action. 

Colonies could often be seized for strategic purposes, another benefit to the parent
countries. In order to guard access to its colony in the Philippines and markets in China, the
United States took possession of islands like Hawaii (which also had rich sugar plantations) and
Guam. These islands became the sites of naval bases like Pearl Harbor.

If it
could be said that imperialism had any benefits for subject nations, these benefits largely
accrued to elites who were chosen to serve as an administrative class. For the vast majority of
colonial peoples, imperialism was a net negative that tended to impoverish the many at the
expense of the few. Indeed, imperialism was mostly beneficial to corporations and business
owners within the imperial nations themselves.