On the other hand, this may also cause to a situation wherein the government would try their chance to regulate it.
That ship has sailed. Governments around the world are already trying to regulate it, force more invasive KYC on bitcoin users than on fiat users, tax it more aggressively than fiat, demand exchanges hand over customer data, employ blockchain analysis companies to track you, and so on.
so a guy who owns a shop could sell a product that is worth 10$ and the next week finds himself with only 5$
If bitcoin did reach global adoption, then any price swings would be minimal. With such a huge amount of liquidity, anyone could dump a huge amount of coin on the market without dropping the price, and with billions of users then the small number of idiots who listen to tweets from the likes of Elon Musk would be very much in the minority. And at least with bitcoin you know at some point the value will almost certainly go up again, as opposed to accepting fiat where you know it will only ever go down.