. I totally get that.
Work out an example - no advice here, and the numbers are made up to be directionally but not precisely accurate.
Let's use a $350k position size for 700 strike puts. If we assume $24k margin for a short put, $20k for the $200 wide spread, then we get to a variety of possible positions.
For csp we can open 5 of these. That's the fewest of the ones we'll consider but is also as safe as safe can get. A full loss requires shares to go to $0 and would be $350k. In practice as the shares go down, 5 of these will be losing money at the lowest rate - roughly 500 shares at risk as the shares go down (so $50k if the shares go down $100). At $500 share price, this position will be down $100k ($20k / contract).
Lowest reward, lowest risk. And taking assignment is always available - you already have the cash in hand with no margin loan necessary.
Selling on margin we can open nearly 15 of these. Let's call it 15 for round numbers and easy math, and putting us into a $360k position. Full loss doesn't happen until shares go to $0 and would be 3x the size of the full loss on CSP ($1050k). None of us think that the full loss is at all likely but it's still there.
If we assume that a margin backed put is pretty much 1.0 delta at $500 share price (700 strike) then this position has a $20k loss per contract, or $300k at the $500 share price. That's a more reasonable 'big' loss.
Round numbers - this position earns and loses money 3x as fast as the csp. Taking assignment is possible and you'll take on a margin loan to fund the assignment.
As there is no insurance cost the received credit will be that much higher.
Using the $200 spread size we can sell 17 of these spreads with a position size of $340k. Max loss happens at $500 share price and is $340k (some simplifying assumptions there, that are common when assessing option positions). As above this position is gaining and losing at roughly 3x the rate of the csp (slightly more due to the 2 extra contracts). The insurance carries a cost with it. If we assume $0.50 per contract then that is $850 for 17 of these compared to the $2000 ($10 option premium, 2 extra options) raised by the additional 2 contracts. So we might think of the insurance as 'free' as long as we're also willing to take on the bit of extra leverage.
We're also taking on a slightly higher impact of loss on a share drop to $500 ($340k vs $300k).
The reality, and this shouldn't be a surprise, is that the two strategies have similar outcomes on such a large drop in the share price. From previous experience I would expect the 700 strike puts to be difficult to manage at $600 share price (really small net credits, and stuck waiting for a share price reversal to make the position manageable again). That's the same for the put spread.
In fact it's the similarity between how the put spread and the short puts behave at these larger spread values that attracted me to them. But I can also readily see margin backed puts being preferable. It starts to look like vinegar or ketchup for one's fries - they're both great, and have adherents that will argue for one or the other.