As @Jawhead999 stated, theoretically everyone can have BTC but in reality, it is impossible for everyone to have Bitcoin or a portion of it. There are limiters and restrictions that make 100% of the population acquire BTC. Just like in the earlier replies, the limitation to access the internet, the illiteracy of one person about Bitcoin, the restriction of a country, and banning Bitcoin, limited access to devices that can process Bitcoin transactions, the interest of the person, and more.
It is impossible for everyone to own 1
BTC for each but it is impossible for them to have a portion of it.
Locally Internet access can be unavailable but if a person has chances to move far from local area, getting access to Internet is possible. If you want, you can buy bitcoin from someone you trust even you don't have Internet access locally. Many methods to own bitcoin and the biggest barrier is enlighten yourself to believe in Bitcoin potentiality and start to accumulate it one way or another.