After 3 years of toiling for a PhD degree I have begun to question the worth of all the investments & sacrifices I have made. I had decided to pursue a PhD in the hope of doing something exciting and intellectually fulfilling, but have realized that an academic job is, most of the time , just like any other job. Most of the work you do is just for staying in the job. True, the level of independence is higher. You can choose the topic you want to work on but difference from any other job ends there. The pressure to work for a tenure is huge and the motto is "publish or perish". Due to this mentality, a lot of garbage gets published. People are always looking to publish in supposedly 'easy topics' instead of working on the hardest & most important problems of the day.
From the point of view of a fresh 23 year old, who comes for a PhD full of enthusiasm and curiosity, working just for a degree can be disappointing. A young, bright, energetic 20 year old coming from a country far far away from USA , the enthusiasm can quickly lead to disappointment if he/she doesnot find a problem or topic exciting enough to work on. Working on an unexciting, dry topic can quickly lead to a questioning of worth of all the effort one puts in. As a PhD student, you sacrifice a lot -your social life, your home, money which you may have been making. The opportunity cost is huge, so if you dont feel motivated then it is just not worth the sacrifice. There are other avenues for unleashing the tremendous amount of creativity and energy which you posses.