Maybe the volatility of bitcoin becomes one of the reasons why it isn't considered as a legit currency. However it fepends on the country, some countries already have, some are still in the process, some deny it completely, because it doesn't make sense for a poor country.
No. the reason is not the volatility. It's not legit because the transactions are made unknown and it's impossible to find senders and receivers.
Volatility is one of the problems when bitcoin is supposed to be used as a currency. But, that's not why governments have not accepted it yet.