Secrets of the Mishkan (Un)Revealed
Chezkiyahu, one of the righteous kings of Yehudah erred in flaunting his wealth when the messengers of the king of Bavel came to see him after his (literally) miraculous recovery (Melachim [Kings] II 20: 12-19 and Divrei Hayamim [Chronicles] II 32:27-31). The consequences, he was told of, were dire indeed. As the wealth was inappropriately used by the king to reflect on his own honor, the prophet foretells that they will be removed and the future kings stripped on their honor. He accepted the decree with gratitude that the decree was averted for his lifetime. The episode is more detailed in the account of Melachim, in which Yeshayahu comes to the king and asks about who came and what they saw. Rashi identifies the parallels between this and G-d's similar line of questioning to Kayin and Bilam. So it should have dawned on Chizkiyahu that he was in very deep trouble even before hearing of the decree. Now what was he in trouble for?
Most commentators explain based on what it says in Divrei Hayamim that he gave into geius [arrogance or setting oneself above what is proper] in showing off he impressive wealth when what the visitors came to be impressed with the miracle of his recovery, which was to be credited to G-d. The grand tour of the treasure houses, which reflects worth in terms of monetary value, was inappropriate in this instance.
In modern society, people are even more likely to attempt to bolster their status by flaunting their wealth or boasting of their importance in public ways. The house has to look impressive, the car must be a luxury model, and the clothes from recognized designers. Yes, one should dress according to his/her means, but the aim of impressing others by one's possessions is a fault of geius. That is not to say that one cannot make use of riches. Hashem had granted Chizkiyau great wealth, which was his to use -- but not to flaunt. The holiest keylim were used, but when concealed, they also served a divine purpose.