. Nobody invest in bitcoin to lose the money and if we are to invest with the mindset that we will lose it someday, then it becomes the same thing as gambling and you don't except someone to gambling with a good proportion of his discretionary income.
It shows that you don't understand the deep meaning of the word "invest with the amount of money that you can afford to lose" it doesn't mean that bitcoin is gambling but it is sending a message to you that you should only invest with you discretionary income so that you don't go and invest beyond your discretionary income.
You can use your discretionary income to do whatever you want, club, gamble, drink, smoke and many more, if it's gone, you forget about it. This is why instead of using your discretionary income for consumption, use it to invest in bitcoin for your future.
Secondly, investing with an amount of money that you can afford to is to let you know that bitcoin investment is not guaranteed to keep pumping and be profitable in the future. So that, you can think wisely and set up other stream of income without putting all your hope to survive with your bitcoin investment in future.
This is because the future is filled with uncertainty and if bitcoin price goes against you, you don't regret investing in bitcoin till death but have other investment/business to survive with. I know that the odd of bitcoin price moving uptrend if higher than downtrend but we wish be prepared for the worst case scenarios and don't only think one side.