Yes and not. When it comes for questions like this, the answer is often depends. Depends on the country where you live. Depends on legislation.
Depends on potential students' demand. Depends on the mode: offline or online. Depends on the subject to teach (what's the most required subject to learn?). And there are much more depends it's hard to remember...
In any way, the depends refer to the term easily. The availability is really good among all countries I know and I never saw an unemployed teacher, but I didn't found any ease here or there. For ex., my former country, after a teaching law reform, requires several years of studying into degree and stages that now count 8 years (the same lenght of a medicine course with the shorter medical postgraduate). And then, to get a job in a public school, a very hard public competition is required. Private schools don't require public examination, but they may require super-skilled teachers. Then comes the opening of a teaching business, but the entrepreneur-teacher must count on several paying students to afford the heavy and burdening tax system. This latter option could be the easier one among all, depending if the subject offered is more or less requested. In my new country, the third option is really feasible (very few taxes, so it's easy to maintain the business open), but not so easy to find paying students. Apart of many people being too poor to pay, a considerable number of students abandon their schooling too soon.