>>With interest rates at zero (actually negative given inflation), almost anything is worth trying because you don't need a big return to come out ahead

You still lose the principal, geez! Like if you worked your ass off for a life time to save a million dollars and interest rate is zero, you're saying "I'll bet all my money on red in a Las Vegas casino", quoting you "because anything it's worth trying".

The interest rate has very little impact on the overall risk of starting a business.