Intuitively I assume that the amount of wealth in a society is the starting point for investment. That is, wealth is invested and by so doing it generates a stream of income. Part of this income is consumed the rest goes to increase the available wealth. The cycle then can start again.
Intuitively, I also assume that when wealth is highly concentrated, then a few people will be in control of the investment flows.
I would be interested in knowing if in macro-ecoomics the investment function depends (among other things) also on the total amount of wealth and on its concentration. I would be interested in research that deals both with the theorethical model and with the empirical analysis of this relationship.