If anybody walks up to me to say he/she is interested in acting I would tell them to join a group, because from that group they will be able to associate themselves with some set of people. Also, some producers will not take the risk of giving someone who did not train under anybody a role. Another thing is that, if an actress for example, does not have a boss, there is a probability that a producer will want to have his way with her before giving her a script, so, it is better to train under someone. For someone who has money and can solely produce a movie, there won’t be a need to train under any boss, such a person just has to be a part of the association and pay dues.