The analogy with e-bikes is not valid.
The four 3d printers I just disposed of worked perfectly and could easily have continued to work. My first rep2 still prints fine.
With maintenance, they don’t wear out for a long time.
The difference between the older or cheaper machines Vs the newer and possibly more expensive is… 1. Easier to use due to a lot of some pretty good software and 2. Way more optimal hardware designs such as toolchanging, super low mass carriages, optimized gantries, sensors, etc. The result is being able to quickly print way more use cases with way better results. So if you buy a $300 machine… it’ll last just as long as the $1200 machine, but it’ll require more work on the users part to get optimal results…. And it may not be as fast.
In the end, if the cheaper machine meets the need it makes more sense, but if it cost the user more in terms of their time it may not.