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I don't see how you conclude that bitcoin is expensive. You can buy pretty low amounts and so for example you can get more than 1,000 satoshis for a dollar. Seems like a pretty good deal. They are only going to get more expensive, and so for example when BTC prices get to a $million, then you will ONLY be able to get 100 satoshis for a dollar. You can think about bitcoin as expensive as you like or agree with you that bitcoin seems expensive, yet I doubt that you are helping the situation if you are actually either agreeing that bitcoin is expensive or if you are even thinking that bitcoin is expensive.
So maybe you don't have enough bitcoin and you are thinking that bitcoin is too expensive to buy at these prices? Or if you think that you have enough bitcoin yourself because you have somewhere between 10 and 20 BTC, then sure, maybe you don't really need to buy more. I mean sure, you framed the issue properly when you are saying that a person with 10 to 20 BTC may well start to feel that he has enough or more than enough, and a person with smaller quantities might feel that he still needs to get more. So why should the price matter for the person who does not have enough? If they don't have enough, then they need more, right?
Expensive is relative to everyone - but people who say bitcoin is expensive are basically orienting themselves and comparing its price between then and now. In 2019 - someone with $4K could buy more than 1 btc - but now, $4K can only buy 0.041 btc. Maybe that's why many of them say bitcoin is expensive - they are always oriented towards past prices. But anyone who has money can always buy and accumulate regardless of how many satoshis they can buy with their money now. The point is only one - bitcoin can always be bought and not everyone will consider it too late.