Popular arts are arts suited to the tastes, needs, educational levels, etc., of ordinary people. Highbrow arts are those considered to be of highly cultivated tastes and skills superior to that of common people. A highbrow song finds few singers, because its range and technique are beyond the reach of most people. A popular song, on the other hand, is less in range and technique; therefore, everyone can sing it.
Schopenhauer said: "Man is either vulgar or lonely." Which can have different connotations. You may read it as to be yourself and not follow the crowd, or not be so aloof as to become a loner, or suit both refined and popular tastes and avoid extremism. As far as tango is concerned, I think the last take is the most wise. Tango is not a highbrow dance like ballet, but a social dance, and most of its dancers are ordinary people. If you are too elitist, there will be few partners for you. Schopenhauer's words, therefore, can also be read as a warning. (See Social Tango and Performance Tango.)