Basically, the reason could be said to be the noble’s fondness of parties.
There are also circumstances to decide holding the party with such a scale and at such a time.
Even the nobles themselves, there are basically many who like to party but you couldn’t say it was 100% of them either. There were many people who are saving up money regularly for such occasions.
Because nobles host extravagant parties, they would be exceedingly evaluated by the elegance of their assets appropriate for a noble.