As long as the procedure is illegal and doctors run the risk of prosecution and ostracism for carrying it out, there will be few cases of euthanasia and only in the most extreme situations.
Once it's legal and all aboveboard, they will start killing folks left and right (it's already happened in the Netherlands with the elderly and the terminally ill.) With no restrictions and no shame, the floodgates open. Babies will be killed for convenience and to avoid expensive hospital bills, just as the elderly and sick are being killed now to open up hospital beds and hurry up the inheritances of their greedy relatives.
These people have no sense. Truly, once you abandon morality you are prey for stupidity.