Hearn stated in his blog post that investing in bitcoin was never guaranteed to yield returns. Bitcoin is not intended to be an investment and has always been advertised pretty accurately: as an experimental currency which you shouldnt buy more of than you can afford to lose, he explained.
"You shouldnt buy more of than you can afford to lose"- I think it's more related to the purchase of alternative cryptocurrency.
Yes there is no guarantee of making profits from altcoins and its very risky to hold them for a long term, but bitcoin can be good in long term so there is not much risk involved in holding it as we are sure that it won't ever disappear just with an blink of an eye which always an possibility with altcoins.