Whether one should invest in bitcoin or not depends on whether you think Bitcoin will become a long-term trusted store of value.
If it does become a long-term trusted store of value, BTC should trade around $2,000,000 a coin (depending on how many coins are lost and are actually in circulation). That is over 100x the price of where BTC is today.
If BTC does not become a long-term trusted store of value, its likely price will be close to zero (unless it becomes a "cool" collectible... which is a possibility).
So if you think BTC has a 10% chance of becoming a long-term trusted store of value, it is a good investment with a nice expected return. It is still very risky but professional investors should invest some small portion of their portfolio in this case.
I really do not understand how did you calculate this $2,000,000 as the value of bitcoin to be considered as a good long term store of value.
What is a good long term store of value? Do you understand the meaning? A good store of value is basically an asset that you can use to hedge against inflation..
So the long term inflation rate is about 3.22%, so any asset that can keep up with this inflation rate would qualify as a good storage of value.
That is why people tend to buy gold and properties to hedge against inflation and use as a "storage of value".
Pulling a figure of $2,000,000 is merely wishful thinking and has no economical basis.