When someone thinks of a password, it immediately gets into constraints of human limits. The limits of Memory, Complexity, Ease of Use and so on. The brain thinks of the password to be easy to remember, generic, related to something. You would want to remember the password when you need it. It is related to things you like, colour, your names, your nationality, favourite pets. You don't want custom and hard characters on it. Remember getting annoyed when your beloved password is now required to have symbols like @#&$ and numb3rs !! !!Arrgh. It's human nature.
===Fine, that's expectable. But How is it compromised? Any quick math will tell you that the complexity will increase by the numbers of characters on it. How is my password generator compromised? Simple, Massive Leaks, Millions of passwords leaks and hacks.
You think you are special but really you are not. Your response to a stimulus is the same as millions of people. Given identical environments and situations and problems, hundreds of people will carry out similar tasks. Given how we shaped to think alike from the schooling, human interaction, pop-culture, religion, books and knowledge sources. In turn how these are also shaped by others before them in a chain. The Sentinelese island people too would be similar in some regards because they too reacted to nature and the environment.
Why the above context you ask? Because when Millions of passwords leaks, The Real Number is much more mindboggling, the odds that your favourite pet name + your favourite 2 digit number was on that list. Now, Anyone who would try to break open the password would first run through the list and find a match. This also means that any new password that you create is already on the list because at least 20 people already did it and there is a chance that it has leaked.
Hence, The best defence against the machines are the machines themselves, the good machines. The sophisticated password generators. The passwords generated by these machines are unique and unguessable. They will generate, save and give it back to you whenever you need it. Here are some good password managers suited for all kinds of needs.