I have to say that there are ways of making billions of gold on Runescape, and using Hunter certainly isn’t what you should be doing if your money making hopes are that high. Saying that if you’re both realistic and pragmatic and you don’t like taking risks in combat related activities then training your hunter level may be perfect for you.
To start with the money you make from hunter easily destroys that of every single other skill. The levels needed to make good money are also significantly less than most other skills as well. For example you need level 91 in the fishing skill to catch sharks, but they’re only worth around 500-600gp at the moment on the Grand Exchange. On the other hand it only takes 63 hunter level to catch red chinchompas and they’re worth around 700-900gp! The amount of experience to level 63 is only around 370,000 but level 91 is 5,900,00! Not only do they make more money but you can start much quicker.
I’d definitely say that catching red chinchompas is by far the easiest and quickest way to use skills to make money in the game. It’s quicker to start, quicker to train, you catch more of the animal then you can catching sharks and you even earn more money from them. It’s literally superior to all other skills in every single way I can think of, and if you’re trying to make money doing anything else I’d honestly stop what you’re doing right now and start training hunter! You’ll learn even more hunter money making methods the more you progress as well!