2. Investing what you can afford to lose: this means that you're using your money to buy something that you can lose at any time. If that's the case, it means it will be unwise for someone who's earning 200k per month to keep investing 40k for multiple years.
Investing what you can afford to lose doesn't mean you are going to lose your money, mate. The thing is that the risk and volatility of the market may make you panic sometimes and probably make a wrong decision, but if you use a small amount of money in investing, believe me, even if the red you won't panic, you will still continue hodling because you know that money is not the money you need at that time, so investing what you can afford to lose does not mean you will lose your money, or what you know you will lose is just because of the risk in the investment.