Rocket science is quite challenging. Learning a rocket science requires skills and talent. Finding a good job as a rocket scientist can also complicated.
Rocket science requires a deep understanding of Math and Physics. To get these skills can be challenging. Yet there are plenty of books available to get better in Math and Physics.
Technology and science created by rocket scientist are usually very expensive. Sometimes the life of people will depend on the success of their work. This means that a rocket science has to work under high responsibility and pressure.
Usually rocket scientists work in the space industry. The industry is small. So that limits the opportunities available to find interesting projects. Also, it makes specialization very competitive.
It seems contradictory but in the space industry there is no much innovation. This is because there are high risks involved in rocket science. Thus innovations in rocket science are usually done with special care. Only recent years, the private space sector started to take on higher risks. Yet an important amount of the funding still comes from the government.