The secret to all these full rebuilds is that the timeline is meaningless to players.
It's a timeline for the staff.
Year 1 - bottom out & chill
Year 2 - push for playoff spot
Year 3 - playoff spot
Year 4 - playoff damage
Year 5 - emerging contender
Then, when they lose, it's "oh, well, you see, sometimes you need to take a step back before you take a step forward in your development.", and it's not like they can trade their young guys. They had to bottom out for them. They also feel they can't trade upcoming draft picks to push their team ahead. Each of those unused future picks are far too valuable. The future stars also need lots of prime NHL minutes to grow, and they need to all be possible future stars. Having a decent star player in an important role absolutely sabotages the development path of the young guys. The sudden success could come too soon. Vets in depth roles are fine, but they need to pretty much be set for the glue factory after the season. The experience and leadership those old heads bring also isn't important enough to keep around as a coach or something. Get a younger set of old guys.