The number 1 reason that the economy of a country will go down it's because of corruption.
If you are really interested in this, you can check out the case of my country, Venezuela. The problem is that depending on where do you get the info, It will be very biased, mostly because the left like to use this as an example of how evil is the world and US bullying a shitty country.
To get to the point, one of the biggest flaws of this economy its that always has been based in a single product economy (oil), its has been like that for decades, but we one of the best and more profitable oil companies in the world, but for the last 20 years this have been milked for the dictatorship of Chavez and Maduro, to the point that when the took this the daily oil production in 2000-2003 was about 3m daily barrels, and now is around 500k (in 2019 was 800k so it's not because of the covid19).
https://www.eia.gov/todayinenergy/detail.php?id=39532#:~:text=In%20April%202019%2C%20Venezuela's%20crude,2019%20Short%2DTerm%20Energy%20Outlook.
https://www.ceicdata.com/en/indicator/venezuela/crude-oil-productionWhy is this? Because of the corruption going rampant in the country, many people that used to work for this company have flee from the country, there is 0 investment on improvements, maintenance or hire of capable personal to keep it running, beside a horrid leak of capital on contracts that are unnecessary or do not ever get done, the refinement from oil to gas stopped completely and we now need to import the gas from other countries.
Countries with single production economy are really vulnerable to falls like this under bad management, but still something like this can dent the economy of anywhere if you give it enough time, the thing is that here they didn't need to hurry, they knew the could to it slowly and put the blame on others with their never-ending victim complex.
A country is said to be not sovereign if conditions abroad affect domestic stability. The country has no resilience. Venezuela is lulled by the title as a big oil producer, even though its production is large, Venezuela is only a price taker, not a price maker. Saudi Arabia alone is known as the king of oil only a price taker. The price maker is of course the US, which has so far supported the security of oil production in many regions.
In my opinion, the fall of Venezuela was not only due to corruption. Systemic corruption committed by almost all leaders of a country has become common knowledge. The mistake is in the governance of the state carried out by the government. lead but do not have knowledge about the right state and create national resilience that can block or minimize the national threat. When Venezuela easily gets dollars from oil exports, Venezuela also opens the door to imports for the basic needs of the Venezuelan people so that dependence on imports is very high.
When oil prices fall, only a few dollars can be used to import and to pay off debt. When the total embargo was carried out by the Americans, Venezuela was increasingly cornered. As a statesman, a leader should make many simulations starting with the question "what if" or the role of the National Security Agency in a country must be active and proactive so that a country can dominate with its resources. When Venezuela was cornered, as usual China and Russia came as helpers, of course, there was no free lunch. Finally, Venezuela is only in the vortex of the competition of the world's big players.