I assume that over time, the bitcoin system will become a bit simpler, and to use it as a currency it will be enough just a smartphone. And with this in the world is a little easier. But it still takes a long time, many, many years.

I know that many people simply do not want to switch to the use of crypto currency, not even because of the lack of a computer or even a smartphone, although this is also a problem. For many people it's much easier to get a paper bill out and pay off than to do a lot of time on a new and complex technology. In addition, if they make mistakes and lose their virtual money or just undergo hacker attacks, many will simply even leave the crypto currency. In fact, this problem is much more complicated than some people think.

 I agree with those who claim that Bitcoin has no goal of becoming the first currency in the world. Yes, this is an ideal asset, but you need to look at the situation. It is a pity that the human essence basically looks for the first flaws and then the potential and advantages. I would on the contrary say that these 60%, sooner or later, will get access to the computer - that's when the golden time for crypto currency will begin. Civilization is moving forward, therefore, most likely, more than half of humanity will become computer users, and accordingly, a potential investor in Bitcoin.

I think thats not fair comparison. Not all peoples in the world having and touching dollar bill but dollar still survive. Bitcoin supply only 21millions and its mean not all peoples able buying and hold bitcoin.

Well going by this logic, more than 50% still don't have a bank account, still currencies are there and succeeded. It's just that bitcoin is very new and little tough for normal people to understand. But eventually it will replace or better to say will run in parallel with traditional fiat as we know it. Let the bitcoin grow a bit and then only we can see how far it is going and how long it will take to replace the fiat entirely.

To my knowledge, bitcoin is created with super-sophisticated technology so even thought the population of many people used bitcoin, it will not stop or fail. I believe that technological renewal is also advancing with the development of the times. Bitcoin is a virtual currency that is very different from the currency currently circulating, therefore the system must be different.

Stuff in your mattress? Really? I think there is less than 60% of the population did that thing. No offense but I can't find the connection of it as the reason why people choose fiat over crypto.  60% of world population cannot access computer, and out of the remaining 40%, some have no internet connection. But if you would visit internetworldstats you could see there that the internet penetration in continuously increasing. As of 2018 internet penetration grew at 1,052% and africa is at the top of the list. On the other hand, bitcoin wallet increases less than 100% in the last few years. That denotes that internet grew faster than bitcoin. It is not the reason why bitcoin will fail; it is more probably users like you could be the reason for this dilemma.

I disagree. Smart phones are everywhere in Third World countries, and they continue to get cheaper.  Additionally, it takes technical skills or familiarization with using the internet especially investing into cryptocurrencies

Who told you that 60% of people do not have access to computers ? And most of people are sing it on apps only so computer is not needed.

you need to learn more about world economy - and also, work hard to make your thoughts and style of thinking a little mature.