AFAIK they have not sold their bitcoins which means you can't really say they've made enough profit to solve their problems. They just have an asset in their reserves that has appreciated in value and economic problems won't be solved just by having a valuable asset "in the vaults".
You are right, El Salvador is yet to sell but the Royal Government of Bhutan has sold about $33.5B of its Bitcoin late last year. However, the country still holds close to 12,206 Bitcoins as of last year.
https://coinmarketcap.com/academy/article/bhutan-cashes-out-dollar335b-in-bitcoin-still-holds-dollar111b-in-btcBut as far as I know , most of Bhutan's bitcoin comes from mining, they have taken advantage of their abundant hydropower resources to mine bitcoin and made a significant profit. But not every country has the same advantages as Bhutan. There are even many poor countries that don't have enough electricity to power their people, let alone use it to mine bitcoins . So I don't think poor countries can benefit from bitcoin and bitcoin can't help them improve their economies either .
To improve a country's economy , we first need to improve the government apparatus and then have economic policies that are appropriate to the difficulties the country is facing . We cannot rely solely on investing in a volatile asset to solve the country's problems , bitcoin was not created to solve those problems nor does it have the ability to do so .