Do I still need to apply for a patent after the improvement of the patented product?

Of course I know. Some inventors think that they can "sit back and relax" after applying for a patent, thus ignoring the later research and development work, and even if new products or improvements are developed, they will no longer apply for a patent. The consequences of this misunderstanding are no different from not applying for a patent. Because when others improve the product and apply for a patent, in turn, it restricts the product upgrade of the original patentee, which will lead to the original patentee becoming an infringer unintentionally. At this point, the original patentee lost his intellectual property rights.