Total wealth is a combination of three independent equal parts: Economic, Social, Intellectual. This can be thought of as three separate buckets. The economic part is an important part of total wealth, but how do you know if your economic bucket is getting close to full.
Well, a Purdue University study summarized in the article linked here (http://money.com/money/5157625/ideal-income-study/) suggests the number may be somewhere around a household income of 60K-95K per year. The study examined 1.7 million people form 164 countries. They found that the amount that gives you a level of optimal day to day emotional well being was around 60K-75K, which is consistent with other studies suggesting this amount for optimal happiness. They also found that 95K is the amount for optimal overall longer term positive emotions.
These studies suggest that as you get closer to attaining these numbers, taking time away from increasing the other parts of wealth(social and intellectual) to continue increasing economic wealth, may not be a good strategy for increasing your total wealth.