I wouldn't say BYU's endowment stinks. True, it's no Harvard ($25.8 billion) but it ranks pretty well in the Mountain West (rounded to nearest million):

TCU - $1.1 billion
BYU - $589 million
Utah - $390 million
Colorado St. - $145 million
Wyoming - $109 million
UNLV - $106 million
SDSU - $68 million
New Mexico - N/A
Air Force - N/A

For Reference:
Utah State - $97 million
Boston College - $1.3 billion

Current AP Top 5
Ohio State - $1.7 billion
Notre Dame - $3.6 billion
Auburn - $354 million
USC - $2.7 billion
West Virginia - $1.1 million (according to US News. Might be a typo.)