Alongside increasing rates of dementia diagnoses worldwide, efforts to seek alternative end-of-life options also increase. While the concept of assisted dying remains controversial, the discussion around its provision for people with dementia raises even more sensitivity. In this study, we explored how the practice of assisted dying for people with dementia is conceptualized and understood using the shared narratives of online contributors. An observational netnography over 20 months was carried out within five open Facebook communities. Thematic analysis was conducted on 1,007 online comments about assisted dying and dementia. Results reflected four central themes and five subthemes: understanding dementia; understanding assisted dying laws; caregivers’ feelings; and moral/personal dilemmas. Findings reveal that the majority of communities’ contributors fear developing dementia. They support the provision of advance euthanasia directives—written by competent patients—to prevent unnecessary suffering, and protect patients’ wishes and freedom of choice when decision-making competency is lost.