infact what you should know was that Bitcoin was successful in El Salvador,
Although investing in bitcoin brings them significant profits, if we talk about the adoption of bitcoin in El Salvador as a currency. I don't think they were successful because as many others have pointed out, over 90% of people there don't use bitcoin as currency.
the IMF is only against the use of Bitcoin as the official currency of El Salvador because the IMF knows what other countries too will follow suits if nothing is done and if it happens that way organizations like the IMF will become useless and less powerful which means that less control over the world financial system
The IMF not only opposed El Salvador's use of bitcoin as a mandatory currency, but also forced the country to not use public money to invest in bitcoin.
I still don't know what the IMF's real purpose is in trying to stop El Salvador or Pakistan from investing in bitcoin. But reasons like they fear losing power don't seem convincing to me because bitcoin is just a currency and it cannot replace the role of the IMF or any other financial institution in the world.