Psychologists are trained professionals who go through almost a decade of graduate training, often serve residencies, and are professionally obligated to stay atop recent developments in the field. Armchair psychologists receive none of this training. There is a very good chance, in short, that they don't know what they are talking about, however well-meaning they may be. Mental health is as serious as physical health (indeed the two are often not unrelated) and misdiagnosis can have serious consequences. Of course it is likely to lead to misdiagnosis. But it might also, because of the stigma often attached to mental illness, lower one's self-esteem. It also might result in a person neglecting to receive professional diagnosis, which can allow a problem to continue untreated. Finally, many problems require treatment with drugs, which can only be obtained through prescriptions, which nonprofessionals are not qualified to prescribe.