The message from the president of El Salvador and the company that he asked to draft the bill specify that there's a huge % of the population that is unbanked, and unable to receive important financial products because they don't qualify due to the current standards in traditional systems. Bitcoin doesn't cost $100 in fees and is currently changing to a system (proof of stake) that will use an infinitesimal amount of energy compared to before.

You can watch https://www.youtube.com/watch?v=-Vcgy1wli9k to understand what the case use is going to be for Bitcoin in El Salvador.