I must come to Britain's defence here - it's behaviour was normal in those times but it did eventually give up most of its "ownership" without actually being defeated in wars. That was pretty amazing.
By modern standards, British behaviour was despicable, but a lot of the invaded countries got enormous benefits - rule of law, economic infrastructure, transport networks etc. Being invaded (not just plundered) by major cultures has generally had good benefits - in the long term - for the invaded nation as they get a lot of the characteristics of the stronger nation.
Again, keep in mind that this is not the modern way of looking at things, which is why we have the United Nations and other international organizations.