Of course ordinary citizens can use bitcoins. But, the catch is that, they will not be able to use it properly unless they have atleast some knowledge about cryptography and security. A lot of terms used in the community will leave them confused. But, the thing is that anyone can learn something if it is an interest or a necessity. Just look at computers

Yes it is , but we should consider the fact that before someone can be able to use bitcoin thy must have gadget , Internet connection and specially enough knowledge for them to access it cause we all know that bitcoin is a digital system and its kinda techy we should be guided by someone who has a enough knowledge in this system.
When someone wants to invest in bitcoin he will be well aware of all these things which you mentioned here. Without internet it is not possible to use bitcoin in any term. Besides many other things are also very important like knowledge, skills, information about bitcoin and the dare to afford lose, because the price in this day is very unstable and volatile. Entering in bitcoin world is full of risks.
It can be used by ordinary people but they can't make profit from it. They can only "USE" it that's all. No benefit, profit, anything good.
One must be rich to take the advantage of bitcoin.