It would not be wise if we try to determine bitcoins longevity just because of the ups and down in it's value in the market . It's hard to know exactly , you never know what happens in the next few years . Bitcoin have started it's journey from scratch . From basically nothing to $20,000 USD . And there will be ups and downs in the market . It's a business cycle . Assuming it's downfall too soon would be a foolish decision for us .

No. I don't think so . Not necessarily . In order to become a  currency bitcoin has to go under the terms with the government . And as soon as it happens bitcoin will be run partially or completely by the government through the regulations. So the final conclusion is bitcoin cannot ruin a country.