A child learning to play the piano will not succeed unless the child has an instrument at home on which to practice  However, good-quality pianos, whether new or secondhand, are costly  Buying one is justified only if the child has the necessary talent and perseverance, which is precisely what one cannot know in advance
Consequently, parents should buy an inexpensive secondhand instrument at first and upgrade if and when the child' s ability and inclination are proven
Reputable piano teachers do not accept children as pupils unless they know that the children can practice on a piano at home.