Early in my career I read about being a humble programmer. In general it was great advice. Being a humble programmer means that no matter how much you think you know, you should accept that you have yet to learn so much more, and realize that there are people 10x better than you out there still learning and not making a fuzz about their abilities, so you shouldn’t make a fuzz either.
This idea really stuck with me, and it helped me become a better programmer. The bad news is that, taking this way of thinking to heart, actually prevented me to become a good salesman. Being a good salesman or marketer is important because, as a programmer, you are selling the most important product: yourself. Whenever you’re trying to land a new project, or even a job, you must know how to tell the client that you’re the perfect fit. If you are worried about remaining humble, you won’t say much and nobody will know what you’re capable of.
Being humble coupled with the impostor syndrome can be a deadly combination for your career. The solution is simple, though: demonstrate what you’re capable of. Work on open source projects, write a tech blog, help newbies in forums, IRC, etc. There are many ways to become known out there and show people what you’re good at, without having to say so.
As long as you remain humble with yourself, you'll get the benefits of continuous learning. Just make sure you have a way of effectively demonstrating your skills when you need to.