A few weeks ago, we decided to paint (油漆) the outside of our house. To save money, we decided to do it ourselves. On Saturday morning, we went to the shops and bought some paint and a number of brushes. We already had a ladder (梯子), so we were then ready to start. We began that afternoon with the back of the house. The next Saturday I went to a football match while my wife painted the front of the house. On Sunday we found that we could not open any of the front windows. We got them all open in the end but I broke three and they were very expensive to repair. Next time when we try to save money, I shall certainly pay someone to do the work.
Why did the writer and his wife decide to paint the house themselves
Because ______ .