It is not uncommon to have AWS/GCP instances stay on for years (since the underlying hardware is abstracted way), etc.
This isn't hard to achieve with reasonable quality hardware and reliable power (which likely includes some amount of UPSes).
The scaling is nice, but as another poster said, 2x swing isn't enough; it would be more effective to buy for your peak and just let them idle on non-peak. If the swing is 10x, then cloud might be more economical. But you also need to build your system differently for frequent cluster changes, vs a stable cluster. Having a short cycle for hardware aquisition is nice, of course, if your load changes quickly.
Comments
This isn't hard to achieve with reasonable quality hardware and reliable power (which likely includes some amount of UPSes).
The scaling is nice, but as another poster said, 2x swing isn't enough; it would be more effective to buy for your peak and just let them idle on non-peak. If the swing is 10x, then cloud might be more economical. But you also need to build your system differently for frequent cluster changes, vs a stable cluster. Having a short cycle for hardware aquisition is nice, of course, if your load changes quickly.