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.
This case happen from people didn't learn from history of bitcoin and still regretting about its potential that's why they always regret without doing any action.
And we can't expect anything from those guys since its like they hard to learn due to trust issue but if they could just learn how big the potential for bitcoin to grow then just see the history of it maybe there's some changes will happen on their decisions to invest on bitcoin.
They should now that bitcoin is slowly entering in the mainstream that's why its so good for them to trust it because if they didn't do anything and continue to afraid for sure in future they would provably regret again why they didn't buy bitcoin on past years where the price at nice figures for them to accumulate or start their investment.