Can it ever be unjust to accumulate wealth?

I picked this question because when thinking back to the three theories of justice the one I can agree with the most is, “Rawls’s Theory of Justice”, as Shaw explains, “Rawls suggests instead that we imagine people in the original position choosing solely on the basis of self-interest: Each individual chooses the set of principles for governing society that will be the best for himself or herself,” (Shaw 102). I believe that is not about the way the wealth is accumulated, but about how smart you are on accumulating it. That being said, I don’t agree with theft or scamming others to build success, but I can agree on how you use society to your best interest to make a great life for yourself. Below I have attached a video where Robert Kiyosaki explains the difference between different types of people,  like those that  use external sources to their advantage and success  and others who instead help with the success of the source, benefiting the source instead.