Of course, this is unlikely to happen with the limited amount of supply that has been set.
I think the limited amount of Bitcoin supply isn't an obstacle, people can buy in a small number (in
mBTC, or in
Satoshi in the future).
If the price of Bitcoin is always growing, it is possible that someday 1 Satoshi is valued 1 dollar. And in the exchanges, people may buy Bitcoin with the small number in Satoshi. However, it is just our speculation that 1 Satoshi of BTC can be more expensive in the next few years.
And another reason, Bitcoin is not a legal currency so most governments still have rules if Bitcoin cannot be used as a legal means of transaction.
Bitcoin is still not a legal currency or not a legal investment in several countries in the world. If the government bans BTC, people have no chance to own it. Moreover, when the governments declare that people who try to own it to be punished and their BTC will be confiscated by the government. So, people have no intention to own it, people don't want to waste their money in BTC.