Quinn was a striver and a dreamer in that he wanted to have great success as a musician. It seemed like some of the other members of the band played for the fun of it. They all had other jobs and family life around their music, whereas Quinn wasn't the best family man and picked up odd jobs so that he could spend most of his time working towards making it big in the music industry. After playing with David Crosby he really believed he would make it big. Later when he realized he may have heard David Crosby wrong, he took a job managing another band who were on their way to great success.
Belle was striving to work towards her grief and to move on with her life. After losing her own son, she was having trouble being around Ted's boys as they reminded her of what she had lost. She knew in time "They will be mine." Belle always dreamed of having a true family life with a husband around.
Ona was both a striver and a dreamer. The boy really helped her see that it was possible for her to make a Guiness Book World record and she began to strive for those goals to honor the boy.
Howard was both a dreamer & a striver in that he wanted to write music that would be recognized and valued.
I believe everyone has moments in their life when they are both a striver and a dreamer. Sometimes the things we dream about aren't really what we want or need and we change our goals.