-When I was younger, I used to worry incessantly about doing something with "passion" and being poor OR having money but hated my career. 18 was a hectic time because I thought I had to pick a career that I was going to be in for 10 years. Instead, what I found out is that there are all these jobs that will pay you better than minimum wage, take a shorter amount of time to train for, and can be done through the internet. Do that instead. If you're worried about being locked in to a 9 to 5, learn a proper skill online and do freelance work. If you're worried about what you're going to do to make money as an "adult", do one of these. Am I the last fucking one to figure that out? Anyway.. I got one, but if you're young, you probably shouldn't bother with a degree. Pick something you think you'd be good at.
-I mentioned it above, but use the internet to work from a laptop. Not only is it more convenient in terms of dealing with people and stress from going outside, but you can potentially move anywhere you want. Go to a country where the cost of living is low, low, low. Download google translate on your phone, then download the relevant languages that you will need so you can translate without an internet connection.
-Being able to move to where you want to go will enable you to get away from people who... don't treat you like you should be treated. That might be open disdain, pity, etc.etc., but try your best to get away from "energy vampires". When I left my small, small life behind, I thought I would be deathly lonely, leaving behind my parents and one or two distant old friends who reached out occasionally. It turns out that I am something like a natural loner.. Not to boast but I have almost never felt lonely at all, approaching 30 years old. Get away from those people
-If you're wondering what to eat to be healthy, do a "paleo" diet as a starting template. It's inexpensive and healthy: just whole foods, meat, veg, potatoes, some fruit. And eat the sample thing every day. This saves mental energy from having to figure out what to eat. Routine is good.