There are many reasons people join Toastmasters: some have specific reasons, such as getting a work promotion that involves the need to make presentations, being asked to speak at a wedding or event, being new to the language or to the country and wanting more practice etc. I'm a member of Toastmasters and feel it has really helped build my confidence. Public speaking is a big challenge for most people, so being able to learn by doing is an effective yet fun way to overcome self-consciousness and really hone this valuable skill.
Apply horse-sense to ridding yourself of self-consciousness and fear: face an audience as frequently as you can, and you will soon stop shying. Dale Carnegie