Rich people and foundations will never tell you when they bought bitcoin. They will do everything only because of the profit. This was the case with Elon Musk when he tweeted about bitcoin, but he bought the coins much earlier and cheaper. As for 100k for bitcoin, I think it's realistic after halving. Maybe in 2025.
All whale traders, institutional investors buy silently while normal traders who see bad market conditions do panic selling. Money Power is everything, if you have money and power to influence the market like Elon Musk then you too can make a big change in the market.
Investors are buying Bitcoin ahead of the upcoming halving and are strengthening their positions because they know the Bitcoin market will go into an insane uptrend after this halving. So those who can think like big investors and are strengthening their positions, will get the real feel of Bitcoin hitting the $100k target.