Grasp all, lose all

This is a warning not to be greedy and try to get everything. In the stock market wealthy investors say "leave something on the table" meaning sell out before a market top. If you stay too long looking for the very top price the market can suddenly drop and you lose all. In other walks of life examples can be: being too possessive in a relationship and getting dumped; demanding too high a pay rise and being made redundant; setting you prices too high and attracting no customers.