When someone says, “don’t invest what you cannot afford to lose”, you might as well not listen to anything that person says. The reason is that this warning is the ultimate removal of responsibility of advice given.
This saying probably started more thoughtful. It should be more appropriately – do not invest in an amount that will cause you to lose sleep if a major price correction occurs. Nobody wants to lose money. However, prices are highly speculative and go up and down. It does not prompt a sell when the prices go down. It is just that when the prices go down, you must hold your resolve to sell.
Saying not to invest what you cannot afford to lose… you might as well go to a casino