A little bit of a correction. It isn't sudden. Neither is it a purchase. Bhutan has been mining Bitcoin for half a decade now. Using hydropower, the small and happy country has been sustainably mining Bitcoin since 2019, back when the price per coin was still $5,000.
Yes, it's the 4th largest government holder of Bitcoin but it's unique in that its coins are earned organically, fresh, unlike the others whose coins are either seized from certain wallets or bought.
Bhutan has been mining Bitcoin since 2019, but that doesn't mean they're ahead in the race. Other countries and companies are also investing in Bitcoin with different acquisition strategies. The fact that Bhutan has "organic" Bitcoins doesn’t really set them apart from others, as many actors in the market also use sustainable methods. Focusing solely on Bhutan's model without considering the diversity of approaches from other countries is a bit reductive.