On the other hand, a scope used in a home lab will probably sit on a shelf and be turned on from time to time when needed. A scope used in a professional environment will probably be left running all the time and will see intensive use. So durability of components, expected number of operations of knobs and switches and mechanical durability will become important factors. I suspect higher end gear will be better able to stand up to the wear and tear of professional use than entry level gear, regardless of specifications like maximum bandwidth.
Not necessarily. For power supplies and other parts the biggest stress comes from on-off cycles, not from being powered on. So a hobbyist who switches the scope on for a short time and then off, and on again only if needed might actually cause more stress to the scope than someone who just switches it on in the morning and off in the evening. Of course long operating hours will cause faster wear to things like fans, but that should not really be a problem for the first 3 to 4 years.
As to build quality, higher end kit is not necessarily built any better. The encoders and buttons used in the front panel are usually the same, and mechanical built quality for a bench scope is already more than good enough even with cheap scopes like the Rigol DS1000z Series. What you pay for in high end scopes is not better build quality but higher bandwidth, faster samplers, more memory, bigger screens, better and much more capable software and faster processing.
For professional use (i.e. 8hrs/day operation) the only worry I would have with scopes from Rigol or Siglent would be the firmware (which is often full of annoying bugs). I wouldn't worry much about the hardware.