If bitcoin reach 100k, the entire market capitalization of BTC should be around 1.8 Trillion. Where do you expect that money inflow from? Perhaps in the future when BTC is fully recognized, adopted as store of value and not restricted in some countries.
Having a marketcap of 1.8 trillion doesn't mean that someone actually put those money into Bitcoin. If we all stop selling, the price would skyrocket to such heights, but there won't be a lot depth to this market, so it would quickly crash back again. In 2017, the $20,000 level existed only for a few hours, and even lower prices like $16,000 didn't last that much longer.
The same people that are predicting 100k will be the first to sell when Donald Trump make a negative tweet about BTC. For now, i don't see BTC above 20k.
More like the people who predict 100k will refuse to sell at 40k, which will probably be the top of this bull market, and then will tell everyone to hodl and be a long term investor.