> Spending 80% of your income on housing is just poor budgeting no matter how you look at it.
77% of take-home pay is closer to 40% of income. It's only a little higher than sustainable levels. When housing costs grow 5-10% per year and PhD programs last 3 years longer than they need to, anyone who had a reasonable budget at the beginning could end up with an unreasonable budget by the end.