What is the authenticity and meaning of the Hadith: "The worst in which a Muslim's wealth is spent is construction"?

There are hadiths that condemn excessive building, some of which are authentic (sahih) or good (hasan). However, these are interpreted as condemning those who build out of pride or extravagance. The hadith you mentioned, however, is weak (da'if).

The Permanent Committee has clarified that the hadiths regarding the condemnation of building vary in their authenticity, and those that are authentic are interpreted as referring to pride and extravagance. There is no harm in extensive building for a legitimate purpose or out of necessity.

In summary, there is no harm in building apartments or buying land to preserve or invest money. The prohibited act is building out of pride, extravagance, and arrogance.