Three types of human activity

The first type is most predominant & solely devoted to making money. Nowadays even education, instead of seeking knowledge, is only a means to get into a lucrative profession. The only thing which differentiates humans from animals, i.e., curiosity about the external world, seems to have been given the go-by.

The second type is the one devoted to getting higher social status (which may also be viewed as the refined version of the "pecking order" present in animal society.) The quest after it is rightly called "the rat race." As long as these two, money & status are garnered, most may even prefer to remain blissfully ignorant & illiterate, as far as they are concerned.

The third & really important human activity is the one where people spend their own good money to indulge in it. Common examples are religious activity (though mostly it is indulged in to get worldly benefits like health, wealth & status.) The other recent addition to the popular activity is travel for its own sake, as a means of enjoyment. Amateur cultural activities like buying & reading books, attending music performances, buying records & audio equipment, learning music as an amateur, buying artworks (not as an investment with an eye on future increase in price.) are an indication of true interest.

As earning money being the primary goal is the theorem of human geometry, its corollary is that spending money on an activity  indicates the real interest of a human being.