Unfortunately until now we haven’t reached the "21 M". If we look at coinmarketcap, the number of coins currently in the circulation are only 17.3 M.


Right, but not just in Bitcoin, I think every market is like that and until now there is no solution for this.
This is because of a fundamental problem that they don't agree with, if you are in their position I'm sure you will do the same thing like they did. This has two sides, on a hand Bitcoin lost its big players and on the other hand this enlivened the crypto market and the spread would be wider because they would fight harder to save their money.
For now I personally see Bitcoin as an investment asset, indeed sometimes I use it for transaction but it’s so rare, especially if it compared to using FIAT.