If Bitcoin becomes the major currency of every country, in countries where the inflation rate is at double-digit, it won't be that bad again. The major cause of inflation is devaluation of the currency, so it is no longer able to afford what it could previously afford. This leads to an increase in the prices of goods and services in the country. But with the scarcity of bitcoin, that won't be a problem.
Also, the political and economic unrest of the country won't affect their currency. I think it will benefit 3rd world countries the most because they are the ones with failing currencies, economies and political systems. All these are just hypothetical, though, because I can't imagine a world where Bitcoin becomes the main currency.
It is true that currency devaluation is a cause of inflation and poverty, but it is not the main or only cause. There are many causes of inflation, and it is a combination of many factors such as poor state management, imbalance of supply and demand, high production costs, disrupted supply chains...
Just like the covid pandemic has caused the economy to stagnate, supply and demand are out of balance...thus causing inflation to increase. Or the war between Russia and Ukraine causes oil and grain prices to rise, and countries that depend on oil and grain imports suffer high inflation due to supply disruptions.
In this case, bitcoin does not help us. The situation will get worse because the government will not be able to print money to regulate, balance and save the economy.