Marketing Mistakes Like These Are Common; Avoid Them!
There is a market online for just about anything you can imagine. If what you do is in demand and fills a need, people will pay you for it.
But you shouldn't risk everything on a single business. The market for your abilities is likely to fluctuate, so it's important to have more than one set ready to sell. You'll need to always be learning new things to achieve your goals.
When providing services to customers, even if you outsource the work, it's always important to have a business grasp of the fundamentals. You can never tell if an outsourcer will finish a job or if they will do it correctly. As the deadline approaches, you may find that you do not have the luxury of asking them to fix it. To come in and complete the task at hand, you need to be well-versed in what you are delivering. To the extent practicable, you should avoid missing deadlines. Getting out of that jam is going to take some doing.
Having reliable resources to begin with will, of course, reduce the likelihood of a situation like this developing. Have the potential outsourcers you're thinking about doing some work just for you at first to gauge how well they do.
Once again, you won't be able to fairly assess their abilities without a business knowledge of the fundamentals of the work they do. Once you have faith in their skills, you may put them to work serving your clients.