My oldest is a 6gb IDE drive from 1998. Dont use it anymore, but still worked fine last I did

I have a NAS with 5x 4TB WD red, 3 running for more than 9 years, 2 for about 5 years. It rund 24:7 on a consumer UPS not providing the cleanest current you would wish for. Never had any problem. What are the odds?