The statement "I value friendship." is grammatically correct and means that the speaker, as a general matter, thinks that it is important to have friends. Only someone who has severe emotional disturbances, however, would not agree with the statement. In other words, the statement is so obvious that it would be unusual to need to say it.
The usual way this is used would be in the context of a specific friend or friends. In other words, the statements "I value your friendship" or "I value his friendship" or "I believe he values our friendship" and so on, are said all the time.