I think of it as being akin to selling picks and shovels during a gold rush. Apart from the currency risk (if USD is not your home currency), the only volatility is in the daily interest rate.
You don't lose money, you just make it at different rates.
Exactly. I've always said don't be the gold miner, be the store that supplies the gold miner. Let others take the big risks. Some will make a fortune, lots more will lose their asses. But either way, the suppliers (or in this case margin providers) make money.