This is clearly an issue. The more unequal the spread of wealth the more problems.
Other way around.
Equal spread of wealth = everyone is poor, downtrodden, and live short brutish lives.
The more unequal the spread of wealth the more prosperous a society is for everyone, even the people at the bottom.
This is no more true as an absolute than the false meme that an equal spread of wealth leads to prosperity for the greatest number. The causes of such wealth disparity is also important to consider.