......If you ask some investor, they will tell you that there is a possibility for Bitcoin to come to zero which i believe that is impossible. Instead, we might see Bitcoin to reach 1 million and above and through that way many will not be able to afford it anymore only the wealthy will be able to buy Bitcoin.
There is always going to be some possibility that bitcoin goes down instead of up and also that it might go to zero, so we should not consider those kinds of going to zero scenarios to be completely outside of the range of possibilities.
Regarding your second point about bitcoin affordability and availability to poor people. I surely hope that bitcoin is always available to everyone and anyone, including poor people, and yeah sure, it is likely that the longer that bitcoin exists, the fewer bitcoin you will be able to buy with the same quantity of dollars.. so that does not mean bitcoin is not available, but instead that fewer satoshis can be bought with the same amount as could be bought earlier.. so even now, as I type this post, we can buy in the ballpark of 1,426 satoshis for a dollar, and someday in the potentially near future we might ONLY be able to buy a few satoshis for a dollar.. so yeah, the amount of satoshis that we get for the dollar is likely going to continue to go down, so if we have already stacked millions or even 100s of millions of satoshis and we are able to continue to stack them and perhaps not lose them then we are likely going to be advantaged over the folks who are going to be brand new to bitcoin in the coming years, whether that is 4-10 years or longer, and whether they have a lot of money to get started or if they stack over the years, there can be differences in the situations including likely advantages of starting out in the stacking and maintaining of bitcoin journey earlier rather than later.