This is so far from the truth. With the exception of the last 2 months and higher oil prices (still much less than previous oil hiking events), air travel and demand has been at record setting levels that have never been seen before.

Spirit screwed themself. Their business model screwed themselves by ****ing off customers for years (front row seat to see if for many years)
The ULCC model is dead and blaming oil, PW, whatever, is just an excuse that wont resonate.

Spirit was able to survive the high oil of 2010-2014 and have record margins. If oil (less than what it was then) is now the issue, well thats an issue with the product and the expenses of the company outside of oil. This is what happens when you have to service debt, high labor costs, and build a crystal palace in FLL.