..... The N S A turns out to be the creators of BTC and they manipulated the protocol in a way to suite their needs. {Invasion of privacy}

..... The price per Bitcoin reach = $10 000 per BTC {Early retirement, here I come}

..... A central organization take over 90%+ of the mining power.

..... If Satoshi is Mark Kapelas 

..... If I am declared bankrupt. 

..... If my country goes to war and I have to relocate to make a new start.

... if my family accept the concept of bitcoin (my family don't trust in BTC in any extent)

I would sell all my Bitcoins if... I can buy my mother the medical devices she needs ^frown^
My father died early and his pension does not cover all the devices she needs, and my salary is barely enough to cover my family expenses ^frown^

If the price INCREASE to $US 1000 per BTC, I can buy her the hearing aid {2 BTC} and if it goes higher, I can pay for the eye or dental operation. ^Smile^

It would mean that she would be able to watch and hear the television and read books again.

I saved some fiat too and will get there some day!

it goes mainstream

I would sell all my Bitcoins if...and only if there is an altcoin which comparably is far more better than bitcoin and solves all the current issue on what bitcoin is facing right now especially the volatility, confirmation time and limit. That is the only reason I will and even if I end up broke without a penny, I still wouldn't sell my bitcoin

I would sell all of my Bitcoins if there's a huge huge huge bubble and its pop is evident. It's incredible how you don't see the top of a bubble when you're in the middle of it!

This is to true while your in it you can think there is no end and it is going to keep going and going but the truth is it will burst and if you are not quick you will be left holding the bag and that sucks..

Today i would sell my Bitcoins if i knew an exchange had been stolen from a shit load of coins and there was due dump. I would hodl some though always because you never know

i would sell all of my bitcoin when one can buy me a house and a supermodel for a wife 

I would sell my Bitcoins if.. I would get 10000x my Bitcoins sold.