An increase in the minimum wage of $15 simply increases the level of prices, or in other terms, causes inflation. It does not increase the welfare and it surely doesn’t make you richer. Let me explain it in a simple scenario:
Imagine you are a small business owner who has hired 4 employees and pays them $7.5/hour each (depending on what state you are in, minimum wage varies). You have 2 suppliers that bring the materials to your business, and their prices have remained the same for a long period of time. You also provide products for another company, who you have been in contract for years as well.
Suddenly, the government decides to increase the minimum wage to $15/hour. You, as a business owner now, cannot afford having 5 employees anymore. To decrease your losses, you will have to laid out a couple of employees to provide them the $15/hour wage and still remain in business. You laid out two people who now do not even have an income anymore.
Turns out that your supplier is having the same problem. They either have to laid out people or increase the prices. They decide to do both. They laid out less of a percentage of employees than you did but increase the prices of their products, which are essential to your business. Now more people are jobless, and prices are higher. You, as a small business owner also have to deal with more expensive supplies.
What do you do? You can either laid out more people or increase your prices too. But you know your employees are essential and that you cannot do the business completely by yourself. So you decide to increase your prices too so that you can still make a profit, remain in business, and keep your employees.
As you can see, the overall level of prices has increased, starting from your supplier, you, and whoever you are in business with. But not everyone is a small business owner.
The people that were hired before now have to deal not only with their unemployment but also with the increased level of prices. What they could buy for $5 dollars before, now it will require $8, or $9, taking a bigger share of their budget, making them go from poor to poorer.
Even the ones who remained in the workforce, they also need to pay higher prices for the products they purchase. Their net income has remained the same, the only thing that has really changed is the overall level of prices, which, for the rich, doesn’t make that big of a deal, but for the poor, it surely does!
The improvement of the economy is measured by productivity, not the level of prices.