Is buying a new machine after five years – with the ability to do so and without affecting one's family – considered extravagance, if the old machine does not fully meet the need?

Extravagance is exceeding the limit in consuming permissible things, and it varies according to people's customs and their levels of wealth and poverty. The questioner should consider his own circumstances, the customs of his local community, and the extent of his benefit from what he intends to buy, in order to distinguish between extravagance and moderation. Being preoccupied with what will happen after five years might be a blameworthy form of excessive hope.