Many people advise newbies to invest only what they can afford to lose but I have done this a few times before and as time goes on they get tired, if I ask them why they reply, 'I don't know it's going to take this long, I have come to realize that telling newbies to invest only what they can afford to lose is incomplete because they don't know how long it will take anyway and most aren't prepared for that.
You don't need to just tell newbies to invest what they can afford to lose. First of all you need to make them understand bitcoin first and the market, how the market is unpredictable. Make them understand no one can predict when is the bear and the bull market, and how long it will last. You need to make then understand the market first. If newbies understand the market they won't be expecting to make profit in a short time, they will exercise some patience because they have know how the market is like. Understanding the market will help one to decide to invest or not.