Being able to hold unto or have faith in what you don't even have an idea about its vision is something that was very difficult for most old Bitcoiners who had a large sum of Bitcoin in the past. I believe it was not only Greg that sold his Bitcoin quite easily. So many other did. From what Greg said, he sold at $0.3 and regret why he could not hold until the price got to $8. That's to say, he would not still hold any coin till not that price is near the $100k zone.
Let's face it - most of us would sell even at 1k, 10k, now we are at 100k - and we won't do it.

Too much time and effort passed to not know what BTC is and what it stands for.
Like now, everyone is confidently claiming that bitcoin will hit $1 million in the future but how many of us can hold on until then? Or will we sell when the price hits $100k or $200k? And we will also be the ones who will regret in the future and be laughed at by investors at that time for not being able to hold out until then.
I bet no one can hold bitcoin until it hits $1 million because like you said it takes too much time and effort. Easier said than done, holding bitcoin for 10 or 20 years is an impossible task if we talk about bitcoin and check its price every day like we are doing.