"A saying I heard once is:
Practice doesn't make perfect;A truth that makes your decision making about what you are practicing, how you are practicing, and who is training you crucially important. If I decide to take a gun training course to improve my shooting, I better do my homework. ENDO occasionally brutally fisks people that set themselves up as trainers and clearly teach people dangerous, if not criminally negligent, behaviors.
Practice makes permanent.
Practice with wise analysis, useful feedback, and application leads to perfect."
The same is true of martial arts. First you have to pick an art and perhaps a style. Then you have to pick an instructor and a school. In the United States, anyone can open a dojo. They may be inadequately trained, they may be unable to teach, or they may simply be a bully, setting up what is a toxic environment that snares new students (at least for a time).
If you have an interest in training, do your research. I am not suggesting what I chose is the "best" in any measurable sense. There will, in all the arts, instructors good and bad. There are other considerations, The school must be close enough that you regularly attend. The atmosphere of the school must be welcoming and new students must be allowed to get into training without fear or hazing. The skill level of the instructors must be high enough to make the effort of training there worthwhile.
If I had to relocate, based on the things I mentioned, I might decide to train in a new art, however difficult starting over might be, just based on the overall qualities of an instructor. Alternatively, if I could relocate to a city of my choice, one of my primary considerations would be the availability of one of the top schools in the art I am already training in.
All of this to say, Greybeard nailed it.