Speaking from very long experience as a swimming teacher and coach (International level) it would be worth an investment. My wife and I, she was a swimming teacher too, made a very good living from private lessons - coaching and teaching.
Take the courses then, and here's the key, get practical experience somewhere. A local swim school or local leisure centre would be a good start and then go private, ideally with a day job.
Good luck.
D. ( ASA Coach. Qualified 1968 !)