Why is there not much more debt leverage?

Interest rates are lower than growth rates in the United States and the euro zone currently. This should normally lead to: High household debt leverage to consume (and therefore a sharp fall in the savings rate); High corporate debt leverage to invest; High debt leverage among all economic agents to buy equities or real estate. However, the only form of increase in debt leverage that can be seen is that of US companies that run up debt to buy back their shares, but not more than in the past. Why this "nervousness" about debt leverage when interest rates are so low relative to growth in incomes (profits, earnings, rents, household incomes)? Perhaps because: Different economic agents do not believe that long-term interest rates will remain low for a long time ; Even if interest rates are very low, there is a constraint that limits the debt leve l .