The reason would be saving vs investing. Saving is supposed to be easy, with the lowest level of risk, which is what gold was and what bitcoin will be one day. Nowadays people thing investing and saving are the same, they're not, fiat distorted this.
Stocks and real estate could offer a higher return in the future, after hyperbitcoinization, but there are more risks to both; the government could seize either, a storm could destroy your properties, businesses could go to 0, etc. Bitcoin just sits there, slowly appreciating without you having to do anything, which means it will be more of an individualized risk-tolerance thing.
I think bitcoin will bring back value investing to stocks.