Bitcoin is not as popular as the US Dollar. US Dollar has been there for a long time so people have talked about it ever since. Before most of us were born, people already know about US Dollar and it has more value than most currencies.
Bitcoin, on the other hand, is relatively new. As we approach a more and more digital world, Bitcoin is also arising. People are starting to talk about Bitcoin but I don't think it will come to the point that Bitcoin is more popular than US Dollars any time soon. But it will, eventually.
There are a few important aspects to keep in mind.
1- Bitcoin is still relatively new - This shows how much potential growth we can realize.
2- Bitcoin offers people financial freedom - This is something a lot people are looking for in times where trust in banks is very low.
3- Bitcoin is the best online currency - Sending billions of dollars worth of coins instantly for $0.05 in fees, is of course impressive.
I am quite sure that these features will make the average joe more than interested in Bitcoin in the coming years.
Let me take the contrarian view on these points, because bitcoin is not a pure benefit with no risks.
1- Bitcoin is relatively new, and has an extremely volatile price history. This makes it a terrible choice for a currency or store of value and nearly unusable for business purposes, which require price stability.
2- Bitcoin offers no more financial freedom than fiat. You don't need to use a bank with fiat if you don't trust the bank. Moreover, banks are far more stable than bitcoin exchanges, which have a long history of losing depositor coins to hacks or insider theft. Deposits in a bank are backed by the FDIC.
3- Digital USD transactions are more stable than bitcoin transactions. In part because of the price instability of bitcoin, also because you can send money through your bank for free if you're a customer. Fees for bitcoin will continue to rise over time as mining income falls. What may look like a temporary advantage now (which you haven't even convinced me of) will become a liability in the future as transaction fees for bitcoin become cost prohibitive.