I am sure that you already know that the more you earn it's also the more you spend and it's very important not to spend more than you are earning because you will be a defaulter because am sure with such stand he or she can not pay back his or her depts.
However, one must learn to cut their costs according to their size. Which means if you want to want to begin investment and saving and keeping a standard of life, you should also earn more. But if you are earning lower, you should maintain a certain standards do that you can meet up.
If we are earning low that means our standard is already high we need more for food, electricity, etc. One thing we do is for sure that we try to earn more, we do more shifts but that does not mean if we have some extra money we just use it or waste it instead even in hard times if we are having some extra money even few cents we should not waste them instead accumulate them.
Once we have enough we could invest them because holding money in the form of BTC is investing. Investing is the most important part we all should be doing, so either BTC is high or low, we should be accumulating BTC as much as we can because in the long term BTC is all profit. But if we thing we are going to need money soon we should just keep it in fiat.