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.
Well, aggressive Investment is not only putting all your funds in bitcoin without having reserved and emergency, sometimes investing %70 of your fund in bitcoin without considering the level of your discretionary and emergency fund can as well be seen as aggressive. if you received $1300 and you invest $200 each every week, making a total of $800 per month left with $500, that is a bad aggressive Investment and surely the person is over doing it. because your bitcoin Investment should be done in a manner that you will not over do it. It will definitely affect you or Put you in a tight corner. If you Invest $800 on bitcoin how much will you use for feeding and running family expenses? Or how much will you set aside for emergency and reserved? Surely if you over invest in Bitcoin, the $500 available amount you will not be enough for emergency and reserved. Definitely it will affect your bitcoin HODLing. Though it depends on you and how you can be able to manage your family. If its you alone you can cope but if it's a large family I doubt if you can manage. The point of the matter is that don't over invest what you can not afford to lose that will make you to sell you bitcoin HODLing down the road because of not having a discretionary fund to back you up.
You can invest aggressively when you have the funds to do that, the most important thing is that you don't over do it, if not it will affect you, and you will end up selling some part of your bitcoin to cover up some emergencies that will arise. Your emergency funds is good to be in a good position size because that is what will determine how aggressive you will be in buying regularly weekly or monthly.