Only hold an amount in fiat currency that you will need to pay for your expenses and debt to be paid. Save the rest and exchange it into investments. This way you are avoiding fiat devaluation due to inflation. Meanwhile, reduce your living costs on its fullest, until you have a decent monthly income through your investments. Many people reject this concept, but that is the solution if you want to reach somewhere better on long term, otherwise you are just going to spend your entire monthly wage month after month for nothing...
Is it ideal? Should life work this way? Of course not. But there is a big difference between how it was supposed to be and how it really is, so we have to adjust ourselves to the harsh reality of our days. We don't have control over how society works, as we are just a little grain of salt, a small gear of the great mechanism, therefore we have to do the best we can on the micro sphere of our existence.
I believe you have described the reality quite well. Ideally, fiat is supposed to be a stable store of value, however with inflation eroding the purchasing power, just holding cash can be compared to watching your savings melt away. Spending the surplus fiat on investments crypto, stocks, productive investment, like land at least will provide an opportunity to keep ahead of inflation rather than fall prey to it.
Simultaneously, I would agree with you that living cost reduction is also a vital component of the strategy. It does not require living in poverty, but being taught to realise the difference between needs and wants is very significant. Not all people realise how little changes in their lifestyle (such as the need to cancel unnecessary subscriptions and to cook at home) can save some money, which can be invested.
One should also be able to diversify. Investing all in a single type of asset might not be a good idea, particularly in a volatile market such as crypto. Other individuals split the two the stablecoins and Bitcoin and traditional investment hence if one side underperforms the other can stabilise it.
Ultimately, you are correct, we are not able to alter the system of the macroeconomy ourselves, all we can do is modify our strategies to compete within this framework. The ones who evolve and create new lines of revenue to rely on and invest wisely are the ones who will come out of the monthly survival pattern.