My I-485 was denied after staying in the U.S. on student status for a long time
I stayed on student status for a long time and was denied at the I-485 stage. I maintained F-1 status while my school was in LA, but at the time I was actually living in New York. I consistently maintained my status, but at the I-485 stage, I was suddenly asked to prove I was attending school and couldn’t. Does that mean all the money I spent maintaining status afterward was for nothing?
Yes, that’s correct. If you had actually been attending school, you would have transcripts, attendance records, and a nearby address on file. If your student status was maintained in name only, USCIS likely became suspicious of exactly that, which is why they requested additional documents. There is also a risk of being treated as fraud and referred to removal proceedings.