If you enjoy building PCs, it's an interesting challenge; plotting and farming have very different performance profiles, and there are multiple strategies for viable builds depending on your expertise (big JBOD vs. raspberry pi with USB drives, etc). Feels a lot like the early BTC/ETH mining days where we were building crates full of GPUs zip-tied together, before ASICs institutionalized the mining process.
> the high performance plotting hardware is only needed temporarily
I'm not sure if you're ever done plotting; if the network space keeps increasing, then you need to increase the number of plots you maintain to keep up -- else you'll gradually farm fewer over time.
I think you probably need more plotting hardware in the initial buildout phase though.
Some are already talking about "plotting as a service", selling disks full of plots once they have finished their own plotting. In the spirit of "selling jeans to gold miners", that might be a viable business model.