You may need an accessible website for many reasons
Your customers include people with disabilities. Your customer requires compliance with accessibility standards. You want to be seen as an inclusive brand.
Accessibility is required by law. You must pass an accessibility audit. Your mission is to provide services to all citizens, including those with disabilities.
You help people with disabilities. You want to ensure that you reach them with your services, and that it is clear and understandable. You employ people with disabilities.
"I do most of my shopping online. Blind people avoid traditional shops. In the past it used to take me an hour, but after the last adjustments it only took me 20 minutes. I recommend your website to other blind people!"