Unless you are planning to have a full system on all the time, renting a loaded 8xA100 machine is almost certainly the way to go for a startup.

As others have pointed out, vRAM is the killer here. this big of a machine is mostly for vRAM coherence, which is a specific usecase.

For almost every other type of job lots of single GPUs with shared disk storage will do (particle sim, rendering, oil and gas, etc.)