This is really a question that can only be answered on an individual level since everyone is different and everyone does things differently.
Me personally, if I had enough btc right now to retire on it , i would cash out now even though I think the value will still go up. I'd be thankful to the "luck" I had and enjoy the new amount of free time I have
. Out of respect for bitcoin and the community though I would try my best to cash out in a way that doesn't hurt the market, ie cash out in intervals.
I planned from the start to cash out about 1/2 of my holdings if we got to 100x my initial outlay. We did and I am. And slowly, but that's honestly not so much in an effort to be 'responsible', but more because I want to maximize my take in case the price goes up in the near future.
My calculus is that if things crash and burn I'll walk away with something in my pocket (and a fair bit.) If the price continues to go up, I'll capitalize on that to. I do like win/win situations, but as often as not one needs to engineer them rather than have them fall into one's lap.
Even though it is not the primary driver in my sales plans I will say that I see some pretty significant risks both to the value of Bitcoin, and to the way I value it as a positive tool for society (which are not necessarily the same thing.) In a word, it is 'coin blacklisting'. I think that it could be done effectively even in a completely external manner (which is what Mellon's company seems to be attempting) and all it would take to be successful would be for the dev team to stand by and do nothing to thwart it. As it happens, it looks like the Bitcoin Foundation and several of the key developers are, if anything, more prone to actively work toward making coin blacklisting successful than to work against it.
Now the success of coin blacklisting (loss of fungibility) will not kill Bitcoin in terms of valuations and thus as a way for me to get rich...in part because my coins are clean and I don't care that much if I am identified since I intend to carefully pay my taxes. At least it will not kill Bitcoin immediately. It will, however, kill completely my interest in the solution as something positive and/or unique.