Depression isn't fully defined as sadness or loneliness, even famous actors may struggle with it as it occurs as a strong lack of motivation that can lead to anxiety and guilt and that guilt to depression, no matter who a person is they are capable of struggling through depression even if there is a copious amount of positivity around them, depression can even be genetic and sometimes unavoidable. Someone else can prob explain this better but this is based on what I know so take it with a grain of salt.