Regarding your question, I think this phenomenon may exist. There are many factors related to the high elimination rate.

First of all, in this line of work, the pressure is definitely relatively high. Some older developers may be eliminated naturally for physical reasons, so there are very few older developers.

Second, the Internet industry is developing rapidly, java technology is changing with each passing day, and new things are developed every year. At this time, some old developers who are content with the status quo and think that they are capable enough may choose comfort, but they don't know that their technology is outdated and it is difficult to adapt to the needs of the new era. JAVA is not an iron rice bowl. It must keep pace with the times. If you don't learn, you will stagnate. Everyone else is making progress. If you don't learn, you will go backwards and eventually be eliminated by the market.

So whether you study by yourself or enroll in classes, you will be at risk of being eliminated. However, the prospect of the Java market is still quite broad and is still developing. Many large enterprises have a great demand for Java talents, and even the demand for senior engineers is in a scarce situation. Therefore, as long as you are strong enough, you don't have to worry about employment.