Levels of aggressiveness should not be measured in absolute terms, but instead within the amount of discretionary income that you have, and so yeah a person with higher income could buy more BTC but that does not necessarily make him more aggressive than someone with lower income and who might be using all of his discretionary income to buy BTC. Maybe we can take some extreme examples.
One guy has $100 per month of discretionary income and he uses all of it to buy BTC.. This guy is quite aggressive and maybe even bordering on over aggressiveness (especially if he miscalculates his expenses or if he does not have reserves in place).
Another guy has $2k per month of discretionary income and he invests around $100 per week into bitcoin, which might be considered moderate and maybe even whimpy.
Of course it is true that someone can increase purchases aggressively when their finances increase from the income they earn. I think everyone has an uncertain income in their job like a monthly bonus from where they work. so their routine of executing $10 per week can certainly change to be more aggressive such as increasing it to $50.
I even often do this where when my finances improve from average or get a bonus, of course I can increase to be more aggressive in the next purchase. So, if income is relatively stable, of course we will return to the initial planning by executing at the usual level that we have done.
Without realizing it, over a long period of time, our BTC holdings increased faster than the initial plan because at each stage we could act aggressively or continue to try to increase the amount of purchases to become larger.
This comprises the investment journey of an average investor. I feel that only the rich are comfortably being aggressive in their investment and not everyone has an uncertain income in their job. There are investors that has a fixed income for a long time and by so doing they only stick to buying through DCA.