Even if you don't have a capital of your own but as long as you have a good skill in trading, you can always borrow some or do pilot trades to be able to produce your own money. Success isn't measured on how one started or if he has a big capital but the result at the end will matter the most.
Big capital traders with less knowledge can lose the capital later on but small capital traders with lots of knowledge can grow their capital later on. Starting with a big capital do also have a bigger risk and I think many professional traders are still humble and down to earth. They don't get confident and use more money as their capital even if they have the capacity of doing so.
But I would never suggest borrowing. There is a big difference when you invest using borrowed money and not. The pressure at the time of trading makes us have a different feeling. I would feel more detached if I used my own money. In fact I've proven.
Regarding the issue of capital, it doesn't matter how much capital you have. The most important thing is that you understand investing or trading. Large capital also has large management. You must be skilled in managing capital, so learn to manage small capital that is constantly growing into large.