Often we hear this saying in the investment cyberspace or social media : You invest what you can afford to lose and more often this is the general advice to newbies. The truth on the ground practice by serious retail investors is  ... You speculate what you can afford to lose. It is speculating and NOT investing! You look carefully at many serious retail investors and investment bloggers on what they are doing with their investment portfolio and SINGLE stock positioning and portfolio management. It is NOT uncommon for these retail investors to build on single stock position up toX% or investment portfolio up to XX% of their net worth! X% or XX% of their net worth is NOT something they can afford to lose. Right? ......