It's more like insecurity through obscurity. Caste discrimination among educated circles is viciously covert. You may not know your caste or your colleague's caste. But the ones who are interested will definitely know it and discriminate on its basis. The discrimination and harassment will make no sense to you, unless something or someone tips you off. It's not like discrimination based on color or gender, where the difference is immediately apparent. You can't distinguish people of various castes unless you go actively looking for it. It's better to be aware of possible avenues of exploitation than be negligent and vulnerable to it.