There are many possible social consequences of large inequalities in wealth. Let us look at two of these.
First, if there are large inequalities in wealth, there are likely to be large inequalities in power as well. Typically, the wealthy find ways to ensure that they have power over society. If there are people who are much wealthier than others, they will be more likely to dominate the society and mistreat those who are poorer and less powerful.
Second, if there are large inequalities in wealth, there is likely to be much less social cohesion. In a relatively homogeneous society, there tends to be more cohesion. People feel that everyone else is in the same boat that they are and therefore they feel a sense of kinship with others. This makes their society stronger because people are more likely to pull together and work for the common good. When there is a great deal of inequality, this dynamic is less likely to occur. Instead, the different classes of society are likely to pull in different directions. The result will be a less cohesive and stable society.
I agree with the above statement. The disparity in power and the need to maintain the gap by those in power is the largest factor. The control of the masses is an intricate game to the elite, generally speaking. Social cohesion is a plague to those wanting to control the masses and, therefore, is intentionally injected with the vaccine of distress, frustration and fear to distract from the bigger picture.