I don't know about the 30%-35% number exactly, but the idea they're getting at is what is the "real" interest rate. Interest rates are all relative. If you can take a loan out at a 15% interest rate is that bad? Well if a bank is offering you a savings rate of 20% - congratulations you just made a lot of money.
Take a look at the T-bill rates in the 80s. To straight-faced say "I'm not concerned about these rates," and make a comparison to interest rates in the 80s is ignorant at best. There was an intentional effort by the government to raise rates in order to fight inflation. We are so far removed from the interest rate environment of the 80s...
https://fred.stlouisfed.org/series/TB3MS
Take a look at the T-bill rates in the 80s. To straight-faced say "I'm not concerned about these rates," and make a comparison to interest rates in the 80s is ignorant at best. There was an intentional effort by the government to raise rates in order to fight inflation. We are so far removed from the interest rate environment of the 80s...