Within each economic system, there’s an inherent maximum potential of wealth, due to the maximum efficiency of the system. This efficiency increases by economic growth, because this normally means more output while the input of manpower stays the same.
If everybody had the same low aggressiveness in collecting that wealth, it would be equally easy for everybody to collect the same amount of wealth.
But there are some very aggressive people and organizations, and some very low aggressive (by character or disposition). Which means, the former will leave very little wealth over for all the others, esp. for the latter. In market economy terms, they “succeeded in competition”, but this only means they deprived the weaker or friendlier people of what they could gain by their working. Because for these, it means they get far less paid for work of the same efficiency than the aggressive ones, they have “failed to compete” … they suffer, because much of the wealth is used up in the luxury items of the aggressive and greedy.
In essence, the problem is that wealth is expendable goods. Wealth is what mankind can gain from nature by using their time for working. But wealth deteriorates; a luxury house needs maintenance etc..
The best way to measure who is having too much on the expense of others is to calculate the “time equivalent” of the construction and maintenance effort necessary for somebody’s personal property. If this is higher than a certain legitimate threshold (like, say, three fulltime employee equivalents of time), this can be said to be unjust.
Also, market economy is such a dumb, short-sighted thing. Instead of investing into the far future by very hight quality products that will contribute to the wealth of the following generations also, it’s all about consumables. Which is the least efficient way to maintain wealth.