"Voluntary" is bullshit.

You can call these transactions "voluntary", but when a huge percentage of the people in America do not make enough money to save, period, that means that all their income is going to necessities (with "a few small luxuries" also being a necessity for any human being).

Many of the companies making the biggest profits are also the companies that own the highest percentage of their respective markets.

People don't have a choice.

The reason people can't save is almost entirely due to the cost of rent/mortgage, which is overwhelmingly driven by the cost of land, especially since the cost of land is modulated directly by the local wages (so there's no such thing as high-income, low-cost areas).

Has nothing to do with "the biggest corporations" reaping "the biggest profits". The largest companies that sell basic needs to Americans make like 10% overall profit.