The vast majority of people who choose assisted suicide are suffering from some of the most horrific diseases like advanced ALS, total paralysis, or terminal cancer to name a few examples. The laws do vary from country to country. I"m not sure of the most recent laws in Switzerland, but I think most at least in the past, anyone could opt for assisted suicide there, if I'm not mistaken. The states that make it legal in the US have much stricter laws, which usually include things like having less than 6 months to live. Imo, it's cruel not to offer help with dying to someone who is suffering from intractable pain and suffering if they desire to end their lives. The fact is that most people don't opt for assisted suicide as our survival mechanism is quite strong in most cases.
Without that option, a good hospice, and they are becoming rare these days, can provide comfortable end of life care. Hospice is permitted to administer drugs for comfort that may or may not shorten life. Dehydration is actually a very comfortable way to die, once the person no longer feels thirsty. I've watched a couple of people die from dehydration and it was a far better, less stressful way to die compared to the alternative. But, unless one loses the ability to swallow, very few people choose to die that way. They don't understand that being fully hydrated means more shortness of breath and suffering as they reach the end. Perhaps more people would choose that option if they understood it would reduce their suffering.
Suicide is a complex matter. There are people who may need help to prevent them from committing suicide. I'm primarily thinking of younger people who may be over reacting to a recent tragedy of some kind. For example, there was a girl in my high school who tried to kill herself after her boyfriend broke up with her. She used a gun and survived but ended up blind. Once she got over the breakup of the boyfriend, she wanted to live. If someone had known what she was planning, perhaps she could have been helped.
On the other hand, I can understand why an older adult with a new diagnosis of Alzheimer's disease might want to kill themselves. I know of one person who did that. I doubt that any physician would have helped her kill herself so she took on the job herself by literally blowing her brains out with a gun. Sure, her family was upset, but it was her right not to face the tragedy of dementia. My 97 year old mother lingers on with late stage dementia in a nursing home. Had she been given the option to be eased out of life before she reached this point, I feel fairly sure, despite her religious beliefs, that she may have opted for that choice. I say that because her biggest fear was living too long and ending up totally dependent. Sadly, that's what happened to my once very independent mother. But, one has to be cognitively intact to receive help with ending one's life, so there is no way for those with dementia to choose to be euthanized.
I've also known a couple of people who suffered from severe depression for most of their lives who eventually chose suicide. That included an uncle of mine. He tried for years to have his depression treated but nothing helped. His wife had left him as she could no longer deal with his misery. He had nothing to live for so he did what was the right thing for him. Would it be right to deny such individuals the chance to end their suffering?