The building or the repairing of houses among us employ many hands, because often a thriftless heir suffers a house that his fat
her built to fall into decay, so that his successor must, at a great cost, repair that which he might have kept up with a small charge; it frequently happens that the same house which one person built at a vast expense is neglected by another, who thinks he has a more delicate sense of the beauties of architecture, and he, suffering it to fall to ruin, builds another at no less charge.
Thriftless implies when a person is spending money in a way regarded as wasteful or extravagant. From the passage, thriftless as used signifies a heir who spends money built by his father recklessly, hence the words from the text that helps to indicate the meaning of the word as used in the passage will be "neglected by another" and "to fall into decay". These shows thriftless and a nonchalant attitude towards money being spent or already spent.
