My Big Question Research

So, my professor and I had a conference. It's done with all the students of the class. I honestly didn't want to go and talk because I'm too shy, but i'm glad i did! When we were talking, I found my cable that I use for Djing, which is part of my big question. My question is, how do Dj's start off? Do they first rent the equipment, do they save up? If so, how long did it take them to create their own business? That's what I want to do. I am the most passionate person about mixing. I take it so seriously which is why I'd rather create my own company or business to make people have a great time, and actually admire my skills! There are some people who do it, but they're either forced because it's part of their grade, or they're just told to do so, but I actually love doing it! Today, I found my cable. The cable that inserts 1 audio aux cord into your phone, or whatever the main device is that will have the music playing. The cable then has the two outer cables that you insert 2 aux cords in, Basically 2 headphone jacks into one aux cord. i need this because when I'm djing, i gotta be able to hear my sound clearly with my headphones for best performances in mixing, the other jack is connected to the speakers that the people will be listening too.
P.S. I lost this like a couple of weeks ago, but finally got it back since my teacher had it on his desk.