You wrote :
Your max downside is $1000
So you meant $10000 RIGHT?
When exactly end of the year -> set a date.
And we will be using Bitstamp right -> send a link.
Yes, because thats what "max downside" means. Its the maximum possible loss for you if you were to bet 0.1BTC because if the price goes to $10k and you have to pay me 0.1BTC that means you are $1000 worth of BTC out of pocket.
End of year means the end of the year. Thats when the clock strikes midnight Dec 31st 2018 (UTC). If at that point it never went below $10k on bitstamp. I pay you $1000 in BTC. Within 7 days.
If at any point prior to that it goes below $10,000 on bitstamp you send me $1000 in BCH. Within 7 days.
https://www.bitstamp.net (you had to ask for a link to bitstamp!?)
I fully realise that this is an entirely one way bet, because in the event you win I will pay, whereas when you lose I expect you to renege. You are an anonymous account, you haven't really got any reputation to consider. I am a bitcoin OG, a real person, with integrity and so if I lose I am compelled to go through with my promise.
Even knowing that to be likely, I'm still making the bet because that's how confident I am that I won't lose.