Recruiters can suffer from the same negative effects of success that anyone else does. The main issue is complacency. Sometimes a recruiter or anyone who has great success can become complacent. Sit back on their laurels so to speak. Sometimes with recruiters, it can also happen because they think they know the business they support too well, or they have a lot of candidates in the pipe. However, the reality is there is no such thing as too many because inevitably, some will fall off for varying reasons such as; change their minds, failing tech screen, cannot relo, HM changing their mind, etc... Then you are stuck with not enough because you became complacent.
In some cases, the complacency comes from thinking they have so much experience they know it all. Trust me you do not. I have over 30 years in staffing and I still attend at least 2 webinars on staffing, recruiting, boolean searches, social media, etc.. every month. Trust me you never know it all, there is always something new, sometimes it is directly related to staffing, sometimes it is Program management, sometimes time management. There is always something you can learn, some new knowledge, skill, or tool you can add to your skills set to make yourself better.
The point is, no matter how good you think you are, there is always someone better. No matter how successful you are there is always someone more successful or a way for you to be more successful. Do not become complacent. Continue to strive to be better or I can guarantee you someone, and maybe even the whole industry will pass you by.