To cut to the chase, I reckon this trader can
1. trade up to 5 contracts
2. achieve a net profit of 24 ticks per day.
5 x 24 x 12.5 = $1500
Maybe i'm being a touch unrealistic but I dont think im too far away.
You make it sound almost realistic, but I think you may be a little further away, to be honest.
I don't believe that a "top 10% retail trader" is really going to trade 5 contracts of ES regularly with $50k capital - much more like 2-3, perhaps.
And I don't think he's going to take 6 points per day off ES, averaged out over the month, either. Less than that, on average, allowing for the reality that he's going to have some losing days, too.
These two factors, compounded together, actually make your estimate a significant exaggeration. In my opinion.
I honestly think about a quarter of your figure is much nearer the mark.