Isn't the patent useful to the first inventor?

Useful. As one of the patent inventors, his contribution to this patent has been recognized, which means that he has gained credibility and recognition in the technical field, which is helpful to gain more opportunities and higher status in his career. Patent right is a kind of property right, which can be transferred and licensed. As one of the patent inventors, he has the right to share the economic benefits brought by this patent, even if he is not the only inventor of this patent, he can still get some economic returns.