Paul returned home after he was injured and refused to wear his uniform, his father kept telling him to wear it as he wanted to brag about his son being a hero and a solider to all the people he knew. As kids or even teenagers, we grow up trying to please our parents as much as we can to make them proud and happy with us thus, why Paul had joined the war as it seemed it was what his father wanted for him and Paul had done what his father wanted.
The views of the elders and the other people in Germany viewing the war and what is happening at the front lines from far away is extremely different from what is actually going on; they do not know the torture and the hardships the boys and the men have to face every single day fearing theta they may be killed at any minute. If the people in your town think that the war is so easy, you not joining I think is only going to make you seem like a coward who does not want to preform his duties towards his country. In summary, as everyone around Paul thinks that joining the war is a person's duty and work after they graduate Paul was pursed in joining he did not want, but he did it as he felt that anything else he preformed will not be considered good enough unless he decided to join the army and fight for the
country.