However, invest only what you can afford to lose, is not what you are applying in my opinion.
Sure, when you start out with the 5k, few percent of your capital, you do, but the $5k became $5 million in your example, which now represents say 95% of your capital. Can you honestly say at that point that you are 'investing in bitcoin only what you can afford to lose'?
Investing is a continuous activity. If you really continuously invest in bitcoin only what you can afford to lose, then you keep your exposure at a low percentage.
Really good point. "What you can afford to lose" is always changing, in some sense.
Well in one sense if you keep the same lifestyle and aren't in debt, you could "afford to lose" your Bitcoin millions. But in another sense, if you had recently won the lottery and had $5 million of new money representing 95% of your wealth, would you really think it wise to put almost all of it into bitcoins to play the "binary bet"!?
This (bolded part). I understand both you and "rationalspeculator" points, but I do not agree with them. I live comfortably on what I generate with my job. I have and I always had 0 debt - in fact I really don't understand how US citizens take loans for everything... jeez man, to buy new furniture for the house too, how crazy is that? In my book, what you cannot pay cash, you cannot afford. This includes cars and real estate. But that's another story.
What I mean is that my life won't change a bit if BTC goes to 0. And don't get me wrong: I'm not saying "hold every single bitcoin till you die". I have already established clear exit points for 50% of my BTC holdings. If all those points are reached, my life will improve A LOT, and I will still keep 50% of my current holdings till the very end.