Your experience is atypical: most people will encounter bad managers in their careers, and more so in this industry, which deifies youth (twentysomethings managing people is a poor idea, period, as are teams comprising only twentysomethings).
Things are further exacerbated by the reality that SV has above-average people in the technical sphere, but way below average people in the people-management sphere. Management in SV is all about people-management, and managers' decisions affect people much more than in other industries. Another factor that contributes to this state of affairs is the high growth rate of companies: people become managers by default, and high growth is difficult to navigate without prior experience. Even when managers have prior experience, when the inevitable fall from high growth occurs, is is very difficult to manage people who turn disillusioned and demotivated. In all this, HR usually are a team that plays only for themselves: they prevent rapid hiring and firing of people who do not perform, causing problems, and they also prevent rank-and-file grievances from being heard by squashing them at the earliest opportunity. This is common in many industries, not just technology. HR is mostly staffed by underachievers with a mean streak --- high-achievers usually opt for engineering and finance, if they have spent time acquiring the specific skills that are needed for these functions, or sales if they have the personality and the drive to persuade customers. The rotten apples end up with HR (marketing comes a close second, but since sales performance directly affects marketing budgets, HR is the best place for these types to last).
Things are further exacerbated by the reality that SV has above-average people in the technical sphere, but way below average people in the people-management sphere. Management in SV is all about people-management, and managers' decisions affect people much more than in other industries. Another factor that contributes to this state of affairs is the high growth rate of companies: people become managers by default, and high growth is difficult to navigate without prior experience. Even when managers have prior experience, when the inevitable fall from high growth occurs, is is very difficult to manage people who turn disillusioned and demotivated. In all this, HR usually are a team that plays only for themselves: they prevent rapid hiring and firing of people who do not perform, causing problems, and they also prevent rank-and-file grievances from being heard by squashing them at the earliest opportunity. This is common in many industries, not just technology. HR is mostly staffed by underachievers with a mean streak --- high-achievers usually opt for engineering and finance, if they have spent time acquiring the specific skills that are needed for these functions, or sales if they have the personality and the drive to persuade customers. The rotten apples end up with HR (marketing comes a close second, but since sales performance directly affects marketing budgets, HR is the best place for these types to last).