maybe, but if at home, it does things it likes and seems happy, then it's ok. An animal's attitude in a clinic and at home cannot be compared at all. Most animals will be nervous in a clinic and many cats will urinate and defecate out of stress from the smell in a vet clinic and people it doesn't associate with.
Maybe at home it is happy and does do things a cat would.
As for 200$ medecine a month, some medications are extremely expensive and are for treatments that render your cat normally acting. let's say your cat is diebetic, the medication is expensive and necessary so yes the costs are high but the cat will still act normally when given the medication.
It is possible she is keeping it alive only thinking about herself, if it is the case, then maybe the vet should explain to her that it is better to have it put down and not perform the 5000$ operation. That's what consultations are for.