FAFSA and CSS Profile

Why would someone not file a FAFSA? Would it be because the parents earn too much money?

If you file a FAFSA, do schools prefer to honour the need over the merit? (because they receive more $?)
Can a school make it a requirement to file a FAFSA application?

Thanks

The school can require you to file a FAFSA if you want financial aid.

But the school cannot force you to file a FAFSA if you don’t want aid at all.

Some schools require the FAFSA for merit aid consideration and you won’t get Stafford Loans if you don’t file the FAFSA…everyone should file a FAFSA