I'm not sure that anecdotal evidence should really be at play here. For instance, the only person that I personally knew who paid a Dignitas subscription chose not to go through with it, but that doesn't demonstrate anything about the population at large.

Terry Pratchett, after being diagnosed with early-onset Alzheimer's, made a documentary called Choosing To Die, which you might be interested in. He had stated that he wished to die by assisted suicide, but ultimately Terry died at home from Alzheimer's.