The effective cost of borrowing is going to be considerably higher than 6% if a regular person is trying to pay for their living expenses with the principal of a loan denominated in cryptocurrency. Think about exchange fees, taxes for any appreciation/depreciation upon sale, the cost of tracking/filing the taxes etc.
As I said it seems like most of the DAI borrowing is being done by people taking out margin loans to speculate on crypto. Perhaps this might make sense for the limited use case of people trading cryptocurrency (which is its most popular yet pointless application), but I don't see it being useful or economically viable for general purpose loans.
EDIT: upon further thought since the loan has to be secured with crypto assets, its not comparable to a personal loan. The equivalent regular finance product would be for a portfolio line of credit. Those have much lower interest rates, fed funds + 1-3% depending on the source.
