The reason there are so many more dentist than Podiatrist is simple. Take that 800,000 person city and assume everyone has decent insurance. To my knowledge most insurance policies cover two teeth cleanings a year and therefore you have 800,000 people needing a 20 minute basic tooth care twice a year. Ultimately, you will need a lot more dentist to cover the demand.
As for podiatrist, it all depends on how much hard work and dedication you want to put in. I have shadowed a new pod who just finished residency who only had 10 patients a day (needs to build his reputation and repeat clients) however the guy he works under sometimes has over 30 patients a day but also has 25 years of experience. Both are doing very well financially.
As I've stated many times on this site, in addition to the number of patients seen daily, it depends on the type of patient being treated and the complexity of the problem. I treated 46 patients yesterday, and only saw about 7 "routine"/palliative patients. The remainder consisted of new patients, post op patients, pre op consults, injuries, infections, ulcerations, aches and pains, etc. Some of my partners can see above 70 patients daily, but on those days they are treating more "routine" patients. Our office is busier than it should be at times, and can get very hectic, but we do have a lot of assistants picking up the slack.
There is an opportunity to do very well in this profession, but I don't know of ANYONE in this profession who has done well and hasn't worked extremely hard. Each doctor in our practice, including the partners, works extremely hard and dedicates a lot of time to the practice.
I have one afternoon of "free time" off per week, and that's this afternoon. However, one of my partners called me that there's an emergency surgery that needs to get done and I'm the only one not scheduled to see patients in the office. So guess what? I don't whine, I don't tell my partners I have plans or it's my afternoon "off", I simply say "OK" and step up to the plate. And they do the same on a daily basis.
That is the formula that ALSO contributes to success. This isn't a part time job, and if you make it one, don't complain about not being successful.