No, prosperity is not only because of wealth, because prosperity has many different meanings. Prosperity can also be because of health. Prosperity can also relate to having a large family that functions well. Each person has their own definition of happiness, which also means they have their own way of defining prosperity.
Prosperity is clearly not only because of wealth. There are many situations in which a person who is not wealthy, or is even dirt poor can arise from their situation and become prosperous and wealthy. Although wealth may help, it is also true that many wealthy do not prosper in life.