The practice of music is, and will be, a way of making a living as good as any other, although it has its particularities.
First, we should differentiate several crafts related to music, including compositor (creating the musical works), interpreter (allowing the audience to listen to the work; sometimes they could also be composers), teacher (showing the craft to others; sometimes they could also be the composers and/or interpreters), and the researcher on musical history or theory (writing about the topic, also known as musicologists since historicity of the 18th century, and who could also be composers, interpreters, and in many cases, teachers).
Second, practicing music has a great deal of similarities with practicing other fine arts, but also many notable differences. Namely, while music has been a liberal art since Antiquity (it was part of the Quadrivium together with arithmetics, geometry and astronomy), other design arts were not. Music supporters have fought roughly for this recognition throughout the centuries, and as a consequence, theoretical music has traditionally been a faculty member, while painting, sculpture, architecture, engraving, etc., were not. The creation of the Real Academia de Bellas Artes de San Fernando (Royal Academy of Fine Arts of San Fernando) in the 18th century was part of this fight, and explains the fact that it took a century to get music included into the academy (although music was not in need of such a "recognition"). Nowadays the roles are reversed, and the fact that music in general is not part of the Spanish university, while other noble arts are, comes to prove the "in-culture" of our time in general, and of our related ministers in particular.
The practicing of music for several types of audiences has been very variable throughout history. Generally speaking, those less qualified act in front of popular and street audiences, ranging from the troubadours so well described by Ramón Menéndez Pidal, to the current musicians acting in our streets (currently even students finance their traveling this way). Those more professional, traditionally have worked for privileged castes, with monarchs, nobles and ecclesiastic figures creating expensive musical chapels in which the members were carefully selected through sophisticated public examinations. These have been very well studied by positive musicology, and we currently know very well the kind of exercises the contenders had to face, the salaries offered, and the obligations of those passing the examination. Considering that most of these job offers came from the Church, several consequences occurred: For some time the contenders needed to become clerics supposing they weren't already, women were excluded from the musical craft, and some chapel masters could reach relevant ecclesiastic dignity. This was a novel entry to the privileged classes, although this normally was not the case of organists, and the rest of bell-ringers and minstrels, who were only beneficiaries or employees.
One of the obligations of the chapel masters was to pass the crafts, which was the reason why cathedral chapters began creating children schools for singers (cantorcitos, infanticos, infantejos or seises, as they could be known among the many names), where apart of taking care of the next generation, they also solved the issue of high-pitch voices in polyphonies, especially considering the complex and extremely expensive possibility of hiring castratos. When due to confiscations the economic power of the Church diminished, the State felt in the obligation of creating conservatories, but this did not happen in Spain until rather late.