Happiness as a function of wealth represents a sigmoid function. This function is different for people (you could go around and define the coefficients in some

Happiness as a function of wealth represents a sigmoid function. This function is different for people (you could go around and define the coefficients in some stupid analogy). The second derivative is the most important. Where that hits its peak is where you can define "financial freedom," and where it hits its trough is where you can define "fuck you money."