"The less you eat, drink and read books; the less you go to the theatre, the dance hall, the public house; the less you think, love, theorize, sing, paint, fence, etc., the more you save -- the greater becomes your treasure which neither moths nor dust will devour-- your capital. The less you are the more you have; the less you express your own life, the greater is your alienated life... things which you cannot do, your money can do.. it can appropriate for you" (Marx 95-96).
All of these things that Marx describes, the dancing, painting, theorizing, thinking, etc. are our passions and our talents, our humanist activities, our "species being." His argument is that capitalism and the force of money put blinders on us and give us a one-track mind: money, money, money. With these blinders on we are unable to see our essence, the wills and wishes that connect us to being human. The more we strive for success in the capital system, the more focused our tunnel-vision becomes, the less we succeed as a human. We deny ourselves our own humanity when we enter into a capitalist system.
Marx makes a powerful argument in that capitalism dehumanizes us. I find myself thinking about parents who never spend face time with their children because they are too busy making money to support themselves or the person working sixty hours a week that hates their job, and then I begin to agree with Marx. I think "Oh man, capitalist has turned us into robots who care more about our accumulation of wealth than about human interaction and compassion." But then I also feel myself wanting to disagree with Marx because there is a piece that he doesn't address. People have choices and freedoms , in choosing a career they love or in not working the extra hours and spending that time with friends. There is a compromise between an ambition to acquire money and also a need to fulfill our "species being."