The flip side of objecting to euthanasia because a tiny minority of people might be pushed into it, is that you are truly just as controlling because you are removing a competent adult's ability to make their own free choices (assuming there is a medical team willing to assist).
Either way, if you force a mentally competent unwilling person into euthanasia or if you refuse them euthanasia, you are not listening to their stated and reasoned desires. This is the core of the matter.
A competent adult who is clear and consistent in their desire should be respected, if there are people willing to help them carry their wish out.
I don't believe anyone should have the right to override a competent adult's sincere desire just because they are afraid that sometime, someone in the future might apply it to them, maybe. Or someone like them. In the presence of extreme intractible suffering it's psychological self indulgence of the highest order.