Keep in mind that there is a huge difference betwen being the common corporate gym personal trainer and a legitimate coach/guru (I don't like the term "guru").
Generally, personal trainers deal only, or primarily with hands-on training with their client. While they may also give advice on nutrition and other topics, this is more of an extension of their job, if they so choose to become proficient in that area.
As a coach, especially a BB'ing coach, one is usually more of a consultant than a trainer. They must be well educated in a variety of different areas, being paid more for what they know, rather than putting a client through a training session. Of course, coaches often train their clients (when distance restrictions do not apply or the client is willing to pay for the coach's travel expenses), but this is just one aspect of being a coach, not the primary objective. Often, coaches will work with clients whom they never see in person, but communicate with through e-mail and/or phone contact. Being a coach entails and usually deamnds comprehensive knoweldge in the areas of training, nutrition, PED's supps, health maintenance, etc, etc, etc.
Whole good trainers can make decent money, it usually takes some time to get to that point and like Kaladryn said previously, you need to be good...not just think you're good at personal training just because you've built a decent physique. There is a lot to consider when traning a wide variety of people with different goals.
Overall, the average trainer compared to the average BB'ing coach are two very different things. Certainly, some aspects of their job description may be the same, but there is significant variance when looking at the big picture.