I think there are many reasons why people still buy bitcoin. one may be because people are more likely to increase the value of bitcoin so once they invest in it they can easily grow their investment and think that it is easier for them to live up to their lifestyle
one main reason is because they still believe about bitcoin future.maybe at this moment bitcoin is bloody, but in two or three years again it will shows the highest price ever.
Now it is not very high but I am sure after holding it some time we will see bitcoin at high price, growing price and high speculation is a sign that we are going to have bright future with our bitcoin, people have strong faith for bitcoin as bitcoin for them a future making currency, it is low now so they are happily buying maximum amount of bitcoin at reasonable price to sell later at high price.