"do you support "euthanasia of economically useless people"? If you don't have a job for whatever reason, should you just be left on the streets to die?"

YES. Old & incompetent people are 'all cost, no benefit' proposition. Children are cost in the beginning, but benefit later on. Saving lives of old and incompetent(lazy, mentally/physically challenged) people is a total waste of resources.

P.S. Just because you don't have a job now, doesn't mean you can't get one in the future or get new skills and work in a different field.