In school we are reading a lot about segregation in the 50's and 60's ,but was it worth for big corporations at the time? Where they losing money because of it and overall was it worth it for the federal government to enforce this, by constructing two separate buildings? Correct me if i'am wrong.
The short answer is an unequivocal "yes". Segregation as legal policy is horribly expensive for any society, regardless of reason but particularly when it is conducted for totally arbitrary ones (which "race" most certainly is). It's terribly inefficient, the costs are quite literally immeasurable, and the "gains" made by such policies are almost entirely a hindrance to society as a whole.
The "best" argument (quotes are for emphasis that such "best" usages are still an overall net loss for the society that uses them) I've read for such policies having ANY benefits is when a group of people, driven into an "us or them" mentality, can be temporarily galvanized into otherwise impossible achievements. The "gains" are always temporary, usually immoral, typically criminal, and occasionally genocidal.
As previously stated, the costs of such policy are almost impossible to calculate, as it is a policy that specifically deals in preventing possibilities. Determining the costs of actively denying some 15% of a country's population their full potential is an equation that is certainly not efficient, and is immeasurably expensive.