[viscanti]

> Paying a handful of percent on debt that will only be borrowed for a few months at a time is, of course, seen as a reasonable cost to smooth out cash flow and leave the other money invested at a much higher return.

It's not just that. They also get to avoid paying capital gains taxes on their shares. So they can borrow against those shares to buy income generating assets that more than cover the interest costs and they can do so while avoiding having to pay the taxes on those gains (especially important when those gains are still short term capital gains where they would be taxed as income).