Here’s the thing: Nobody can predict the future, and any jobs that are hot right now might not be hot in 5+ years. When I entered college in 2004, some of the hot areas to go into were law, real estate and finance. You can imagine what happened when people who pursued those fields graduated into the crash in 2008 (or the ones who pursued law school finished in 2011). Right now computer science is on fire, but in 5 years maybe the tech bubble bursts or something happens that depresses salaries in the field.
That’s why it’s important to pursue something that’s based on your interests and individual skills. I’m not saying don’t be practical - you should - but combine that practicality with interests. You don’t want to be stuck doing something that makes you miserable, but you especially don’t want to be stuck doing something that makes you miserable that pays pennies - or worse, nothing at all - because it was cresting right around the time you went to college. You don’t necessarily want to pick a career that is in a “golden age” right now.
So first of all, if you are a junior in college and - by your own admission - you haven’t heard of many careers, that’s a perfect reason to wait to declare a major. Wait until you get some more exposure to the many careers that are out there. You don’t have to declare until the end of your sophomore year, and declaring in freshman year of college won’t put you behind the curve.
There are a few exceptions; nursing is one of those that you should know going in so you can take the appropriate prerequisites. But there are ways to pursue nursing later on even if you don’t originally know that’s what you want to do. Also, nursing is not one of those majors you should pursue because there are “many choices and levels.” It takes a particular kind of person to do the job - for the first few years, at least, you will be working medical/surgical nursing on a hospital floor, working all kinds of cases from banal to ridiculous. You have to have a caring spirit in you willing to take on that work. Plus, you’l hear all kinds of ballyhoo about a nursing shortage, and it’s true that there is one. But the shortage is really in particular areas of the country in fewer people want to move, like rural areas - not in big cities like New York or LA - and in particular lower-paid fields of nursing like nurse faculty (nurses who have the level of education and experience necessary to teach college-level nursing can make a lot more money doing other things).
You’ll get better suggestions if you maybe talk about your interests a little bit - I can suggest careers but they may be careers that you’ll hate.
Also, as a side note, do know that it’s very unlikely you’ll be upper-middle-class coming out of college. Average salaries for recent college grads are in the $30-50K range, maybe a bit more for well-paid engineers, software developers, consulting and finance/banking.
And people do hire optometrists; not all of them own their own business. Some of them go into group practice and some attach themselves to a national chain like a Pearle Vision or Lens Crafters.