That's actually one of the flaws of Austrian economics. Mises just postulates that certain of his personality traits apply to all humans and ignores the personality traits of other humans. He is also confusing the informational theoretical world inside his mind with the harsh reality of the real world.
The word "capital depreciation" kind of summarizes all sorts of flaws. Gold is considered an ideal currency yet it suffers from no capital depreciation at all, while all other forms of physical capital depreciate. Once you have built all the houses, roads and schools, etc there is nothing left to build. If you happen to have built too many schools, then you are a fool and should convert the school back to gold by demolishing it and selling the scrap or in other words, idle capital, that is left to depreciate, must be eliminated.
When you think about this, this is secretly rewarding monopolies and all sorts of other nonsense that capitalism suffers from. For 10 people there are exactly 10 jobs. If a workaholic hoards a job by working 80 hours per week to retire early, then somehow there won't be enough "jobs" for everyone. This gives employers the upper hand during negotiations as employees start competing with each other instead of employers competing over employees. The current system is also dumb because it tries to represent capital depreciation through an increase in the price level i.e. 2% inflation targeting.
