"Why haven't the earliest participants sold their Bitcoin, and some haven't even touched the coins in their addresses, considering the high price of Bitcoin?"
Someone has already told you some reasonable reasons in the second post after yours
[1] - so it already represents the general opinion about your question. I agree with him although several other reasons are also worth knowing, especially because you are still curious as a beginner.
[1]
https://bitcointalk.org/index.php?topic=5474885.msg63195078#msg63195078With a private key, Bitcoin will always exist. I ask questions with a learning mindset, and after understanding, I feel that Bitcoin is like digital gold. It's basically difficult to have it after not having it in the early stages, after all, the price is too high. Although I don't have one, I hope Bitcoin and forums are getting better and better. I hope I can have it in the future. Those who possess are truly lucky
Bitcoin will remain on the blockchain regardless of whether you still hold or store your private key or not. Losing your private key will make you lose access to your wallet and the consequence is that you will lose your bitcoin forever.
Then from that - you don't have to buy a lot of bitcoin if you don't have a big budget. Buy as much as you have because basically you can still buy bitcoin even if you only have $5 in your account. Start from a small budget and increase it periodically according to your budget capabilities rather than nothing at all. IMO - This is the best way to start.