If age was that important you would expect to see states move lower as average age increases in a somewhat predictable manner. Florida, and Maine however are right near the top despite having some of the highest age averages. Meanwhile, Texas, Nebraska and Oklahoma which have always had a young average age pretty close to Utah are much lower.

The other thing I see here is Utah has been the youngest state for a decade or more but has only had a DTI this high in the rankings twice before now (2007 and 2008). While the age is a factor, looking at the larger picture why is Utah suddenly moving so high? Real estate like many mentioned seems the obvious answer but the data still shows people taking on more debt for this relative to their incomes than in the past. I think thats relevant and can't be simply dismissed because of age demographics.

I will also add that if all 18 year olds are included in this data set and Utah has a disproportionate number, that would also seem likely to push Utah lower in the rankings not higher. I think that point actually strengthens the argument the Utahns are spending in excess. The only significant debt an 18 year old in Utah would normally carry is student loan debt which we know is much lower in Utah than the national average and we have high numbers of students that never take on any student debt at all.