I have a small disagreement with your first point. It can happen, and even more often there are no shares to borrow from your broker at all, but it's not "often

I have a small disagreement with your first point. It can happen, and even more often there are no shares to borrow from your broker at all, but it's not "often" that way. Options trades are not brokered between two clients the way equities are. You're trading with a market maker, and that's true whether you're buying to open or selling to open. When a market maker sells you a put, the first thing he does is offload that risk by shorting the stock. He's not paid to take directional risk. And that put premium needs to cover the carrying cost of that short position, in addition to things like implied volatility, time value, etc. You are right that you get leverage with options, but there is no free lunch.