General opinion is that a side job is one that supports the main income of an individual, often times perceived as something that brings little money to add to what you make from your day job. If Mr X earns better from a side job when compared to the income from his career option, does the side job still qualify to be called a side job?
Work is work and money is money regardless of where and what you do to earn a living except for fraudulency. If what you so call side job or menial job fetch you good income than any office or white collar job then you are good to go, once you ain't lazy, scamming, or involved in any unethical moral vises, this so called side jobs can gibe you sort of peace of mind, independency and an opportunity to self discovery and if you're the type that can manage and knows how to blend two jobs together in a mutual way that such is not affecting the other then is a welcome idea.