There are two main kinds of retirement savings, those where the retiree is in control of where their money goes - in which case they can choose to invest it as they wish. In an index, a company or anything else, and those where a company is investing on their behalf but with a legal obligation to pay out.
Now, if the company goes bust then that is not the fault of HFTs or managers skimming. Either they failed to make adequate contributions or they simply went bust because the business failed.
If you invest your money in ACTIVE MANAGERS then you'd best know who they are, what they do, and why they think they can win in a negative sum game. By definition very few actually can.
HFT is not the cause of pensioners going without - that is a combination of lack of contributions (based on unrealistic expectations) and poor investment decisions. They don't prevent you from spending all your money on Apple shares and making a killing, and nor are they to blame if you invested in Northern Rock and lost everything.
It is a fact that more money is spent on portfolio transaction costs for large pension schemes than any other cost. It is also true that much of it is unnecessary. But these are functions of investment choices based on active management, along with poor implementation and usually high management turnover.