Of course it is not.
It is possible that many traders increase their equity after a while, when they are more confidents (what is very subjective).
However, if you add today one million Euro to any trader, this trader won´t be better from today on. So, adding more equity prove nothing more that a determine trader is risking more money.
On fact, after adding one million Euro, most likely the trader wil have worse returns. Because it will have more divergence and much more mental stress.
Therefore, the statistics usually are made on biassed factors that the person who want to prove something takes to make its point. And also, the outcome of those have to be interpretated, and every person has a personal view or interest to made the conclusions look on its side.
You or me can bring here stats based on some numbers, but the fact is: a higher equity don´t make any trader better. You can´t prove I am wrong on this one. Nobody can.