So this is an interesting point @MrMadila, but I think its important to understand the supply distribution schedule as well. Please be mindful that I could be wrong, however, this is what I have gathered.
Yes there is 2 billion FIL in supply, however, ~140 million has been distributed and ~27 million has been burnt
The FIL foundation (100mn tokens), Protocol labs team and Protocol labs (300mn tokens) have a 6 year vesting schedule (linear) and we are about to enter year 5.
10% of the total tokens was allocated to its ICO (2.5% of total supply) and SAFT (7.5% of total supply and had lockup of 6mo-3years).
The remaining 70% of tokens are distributed through storage mining (55%) and mining reserve (15%). The mining reserve will not be distributed unless voted on by the community.
The big question mark then becomes how is storage mining distributed. Im not going to claim to understand this, however I do know there is a burning mechanism attached to this distribution, so 55% will never be reached. To date ~27mn tokens have been burned. Spacegap - Dashboard for Proof of Space. Further, the distribution will occur over 20-30 years.
I am working on creating a supply distribution schedule, but the moral of the story is I think this assumption is misleading and the real supply inflation is much lower and does not makes sense to look at the FD market cap.
I will follow up shortly, but wanted to get this opinion out there. Moral of the story is, I am not sure the answer yet, but 2 billion supply seems like an improper number to use right now
Here are a list of resources I found that explain this in more detail.