Gold has the lowest amount possible out of all three in your comparison but easy to fake.
Real Estate has the highest amount possible out of all three and will always grow with a steady growth, someone always wants to buy and its getting fewer and fewer.
Bitcoin has the medium amount possible out of all three but you can't and assume the next 15 yrs growth because of the last 15 yrs.
That is why a lot of people regret from not buying Bitcoin earlier because of that assumption. Although we can't assure that what happens today can be the same in the future, that is faith and trust. Risk-takers don't choose to be safe but rather prefer to take more but look, these people are earning more compared to those who invest in nothing.
Some people sell their gold for Bitcoin.
Some people sell their valuable properties for Bitcoin including land.
There is only one reason of these things --Bitcoin is the majority choice by most because of its growing price trend.