This is a very strange interpretation. Lost revenue relative to what? Not having it? Is the government losing revenue by not taxing the bottom 50% of income earners, too?

The tax code is structured this way to incentivize saving for retirement. Social security exists for the same reason. The government allows you to defer taxation in these structured vehicles so that you are better able to care for yourself in your old age, so that the government doesn't end up footing the bill.

These accounts are no more a "give away" to the rich than the progressive income tax schedule is a "give away" to the poor.