In any event, this so-called reserve fund is supposed to be earmarked for repayment of the US's debt, something I'd find extremely risky at best given how volatile bitcoin is.
Bitcoin is volatile and times for x20, x100 or x60,000 are long gone away. I believe in bullish future of Bitcoin, but I am realistic that it is volatile in short term and within one market cycle and times for super parabolic bull run gone.
Bitcoin will only help the USA. to pay partial of its national debt, not all of its national debt. It's impossible.
As to why those countries would need to follow the US's bitcoin buying spree, who knows?
It is like domino effects. It's all related to money and benefit so if people as individual investors, institutional investors or governmental investors, have many reasons to join a good party.
El Salvador is a first nation started governmental investment in Bitcoin, and some years later we have Bhutan. Soon, more countries will join Bitcoin party and there is enough time and chance for their participation.