There's absolutely nothing to stop people from using bitcoin as a means of payment even if your country doesn't legalize it. Even transaction can be carried out in private between sellers and buyers, especially when both agree on the payment instrument.
A strong government could make buying bitcoin very challenging. Binance, Coinbase, etc. bank accounts could get blocked. By blocking bank accounts, the majority of people can no longer buy or sell bitcoin. Because of this, complete privacy is a requirement for cryptocurrency (sound money).