The lesson is; bitcoin is simply money that has more value than every other money. Bitcoin is simply a currency that is better than every other currency. I understand it's more technical than this, but in this context, that is what it is.
Adopting a new currency doesn't fix every single wrong that's going on in that country.
Adopting bitcoin doesn't mean there will be no security issues, inflation, unemployment, etc. Bitcoin is simply money and if you don't work for money you won't get it.

Let's say the government has a bitcoin reserve and they make a profit after 10 years, there's no amount of profit bitcoin will give them that can help them eradicate poverty from the country or turn the economy around. They still need to do the needful if they want to have an economy that flourishes. They have to create jobs to battle unemployment. They have to make their environment investor-friendly and make sure citizens have money to patronise foreign investors before foreign investors can come into the country.

Adopting bitcoin as legal tender is just one thing out of a long list of things that they need to do. Unfortunately, the body (IMF) that's supposed to help them grow sees things differently from them and has its own agenda.