its sustainability and tight security.....safety and reliability....
to invest security may still in question to invest in bitcoin. because bitcoin prices are still very volatile and may change at any time and it will make a sudden poor
Maybe he is just referring to the security about that it cannot be steal by someone that is going to attack your bitcoin wallet. But even the price of bitcoin is volatile and unstable I would say that take it as an advantage not a negativity about bitcoin. Because if you are going to think about it positively you are going to realize that it is really a good characteristic of bitcoin.