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.
There is another side to the coin, Bitcoin is becoming a heavier asset and every time it reaches a higher price, it becomes more difficult for it to grow due to the large capitalization of the asset. Yes, Bitcoin will most likely continue to grow in price, so buying it now may not be the worst idea, but perhaps in the coming years, it will not be able to grow more than several times. I only know one thing, that buying Bitcoin has always been a good idea, and in the future it will also grow, but perhaps not with such a profit as it was in the past.