Thanks for your engagement here, btw!!

>no loss if nothing happens, profit in the hedge account if market crashes. If such an investment vehicle existed, why wouldn't I put all my money into it?

Not quite. If the hedge is perfectly placed, I wouldn't make any profit or loss OVERALL.

>if the lender you are working with would do a rate lock extension.

I did consider this, but this wouldn't be an ideal hedge. I would win only if rates go significantly up. Because of the upfront cost for locking today's rate for 6 months, I would be betting the rate goes up. I feel I can do better than that. I personally feel things may remain the same then in which case I'm essentially losing money for locking the rates.

I certainly aim to stay in the house long term and that's the main reason why I bought in this crazy market.