It is the early days of bitcoin that we should be very much cautious about the advice of investing what you can lose into bitcoin. We can take such advice seriously for shits but for bitcoin, invest the amount you want to use for investment. If you have $10k and you want to invest $3k, invest it, even if you can't to lose it.
Your money is not going to loselt in bitcoin and we all know about it. So, what is the essence of investing only what you are able to lose?