We often are ungrateful and if we look closely, we are blessed with so many things for free, be it free oxygen, water when we are thirsty, opportunities to work and earn money and the possibility to buy good foods and experience this universe. I guess it's human nature to forget importance of stuffs which are available without asking 
That is life for you, people don't always appreciate the little they have. Human have that nature of not being grateful, but I pray we should learn to get the attitude to be grateful with everything we have around us.