The possibility of BTC over taking Tesla and Facebook is very much possible, and that might even take place before the year 2021 ends. No one thought that the price of BTC will go this high, and no one expected its market capitalization to get this high. With the current bull run we are facing in the market (though, the time for correction is inevitable), BTC getting to the top 5 ranking is not too far. Where there might be challenges will be between BTC taking the number one position from Gold, which is and has being the most precious stone from the existence of man.