Well everything is related and Food is the most priority. But don't buy too much food. but buy enough to meet our body's balanced nutrition. And actually the money to meet the need to eat is not too big. Compared to the money we spend for other purposes such as internet bills and so on. everything must be adjusted to the right portion so that you can still leave money to save and invest.
If they already earn enough every month then they should be able to set aside for investment, even if it can only be 20% of the total salary, it doesn't matter as long as we can adjust the cash flow we have.
Food has indeed become a priority, whatever we do is in order to be able to eat to survive with nutritious food of course it is a must for us to stay fit, well about other payments such as rent, internet, electricity and other maintenance bills that must be determined from the salary we get it has become a routine before investing for sure they will prioritize what is needed, maybe if there is more than monthly money they can invest in bitcoin.