"far more complex maths".Not sure how this is relevant, but ok,...

"far more complex maths".
Not sure how this is relevant, but ok, I believe you.

Then why would you even be using 47% in the calculation when you will never pay 47%?

Other than that, the average income is about ~$90K
ABS average income

It is not going to relevent to a lot of people even if it was possible.
At that income the effective tax rate is <23%.... a lot less which in turn will make profitable trading much easier.



Back on the 47%....

Show me the formula used to calculate a taxable income amount payable that will result in you paying 47% of your taxable income to the ATO.

CGT, dividends, salary all of it is added in one amount ( taxable income) and only then are the progressive tax table calculations applied.
The bottom line is that you pay effective tax rate.
That is the amount of money that will be owed to the ATO.

Let say I'm and investor.
I earn dividends and CGT.
For simplicity dividends is paid unfranked and you do not qualify for CGT discount.

$100,000 in dividends
$150,000 in CGT

How much tax (amount and tax rate) do I pay on the dividends?
How much tax (amount and tax rate) do I pay on the capital gains?