I would say it is a sin to be purposefully irresponsible with one's finances, such as getting into unnecessary debt that one knows one would not be able to pay off (e.g. buying a house far outside one's means with debt one cannot afford to pay off).
If one provides not for his own, he is worse than an infidel.
Borrowing money that one knowingly cannot pay back would be stealing, in my opinion.
Now, if a tragedy happens that disables someone unexpectedly, I would think that would be excusable. I am talking about intentionally making oneself vulnerable just to enjoy unearned luxuries in the present.