[jimbokun]

1. Because many people can easily afford the tools you need to learn programming (like the author said, a used MacBook, or any computer that can run Ubuntu). I'm pretty sure getting a hold of all the gear you need to be a practicing dentist will be much more expensive.

2. Because you can probably learn enough software development to do something useful in several months, maybe even enough to succeed in an entry level job. I think learning enough dentistry to actually practice it will take longer.

3. Because programming is much more lax about credentials. Sure, many employers require a CS degree for anyone they hire, but many do not.