I doubt that anyone here is making a living trading a 100K account. Can it be done, in theory it's quite easy. In reality I have my doubts.
A lot successful traders start out with small amounts of capital. It is what you do with that capital which is what matters. So, $100,000 is plenty. Option Sellers had control over what? $120 million and lost every penny and ended up owing monies on top of that? Ever hear of compounding? Banks make out like bandits because they compound their monies? They get their monies from the US Federal Government at 2% and charge us 18% or more for credit card interest when we use their monies. Now, a competent trader can multiply his monies at an even faster rate. Most day traders start off with $1,000-$2,000. Take the day trader, he is compounding his monies at a fast rate, every single day. The only flaw in most day traders is they risk so much of their capital on each trade, risk management be damned. One day, they will blow up their account. Eventually, you will have losing trades even if you are a very good trader. That will be enough to destroy your capital base. That is the reason most day traders fail but, they will have a period of success where they run up their monies from a few thousand into hundreds of thousands of dollars.