The main reason stuttering "lessens the chances" of achievements is societal burden from both strangers and people close to the stutterer (family and friends). Having supportive parenting goes a long way to helping them achieve what they want in life, despite living with a stutter. I can say now as a 36yo who began stuttering at age 6 and wasn't able to receive speech therapy until age 30 – the largest barrier to professional success and enjoyable social interactions for me was letting the stigma of stuttering and some people's judgements define me. After my mindset about stuttering changed, my other outcomes changed immediately too. Looking back, the first step to building a foundation that doesn't cast stigma on a person's stuttering is during their childhood. Children are sponges of their social environment, so as a previous commenter mentioned, presenting a stutter as something "bad" (i.e. resulting from "damage" such as a head knock) is not helpful – a child will likely internalize this, which increases anticipation and anxiety when they speak, often worsening their speech blocks. It helps to think of stuttering not as a part of the stutterer or something the stutterer is *doing*, but as a verbal block *happening* to the stutterer. There are some great books available for parents with children who stutter (with tips about not interrupting them or completing their sentences, etc) to better understand what they are experiencing. Attending speech therapy with them may also be enlightening and rewarding for both of you, as the process isn't necessarily a "cure" but moreso an understanding of what stuttering is, and finding solutions to manage it.