Rich is defined as "having a great deal of money or assets" but abundance is subjective. It is measured by comparing it to other quantities. Therefore if everyone is rich then no one really is since everyone would have approximately the same amount of money (assuming that's what you meant in your post) and prices of all products will obviously also increase.

Most people will also not settle with having the same amount of money with everyone else so they would probably try to find an additional source of income or a job. Thus bringing everything full circle. People are back to working since they would need to earn more due to prices of goods also increasing. Additionally, people are envious by nature so even though there would be no reason to steal from each other the people will still find a reason and a way to do so.