Quote from AAAintheBeltway:
The same rules of probabilities apply to them as you with your $20,000 account. The same risk of blowing out.
Yes, someone with a small account can make eyepopping returns in an historic bull market for a few months. Good luck keeping it.
If I risk $1000, I can replace it many times a year without discomfort. With a $4 margin requirement, I can buy 250 ounces of gold. In other words, my potential gain is much larger than the loss simply because the $1000 is replaceable. A large institution doesn't have the same luxury