80% of the 21 million available Bitcoin has already been mined, leaving only 4.2 million BTC available and the next adjustment of the reward for mining will be in June 2020, according to the current hashrate.

On January 13, an important situation occurred within the Bitcoin market, since at that time the figure of 16.8 million Bitcoin extracted was reached, something that represents 80% of the total. This means that the amount available to be obtained is 4.2 million Bitcoin or 20% and that the number of Bitcoin obtainable is finite, encrypted at 21 million BTC. This limit is established in the Satoshi Nakamoto whitepaper, established in 2008, as a method of establishing a limit and after reaching that figure, no more can be extracted from this cryptocurrency.

The fewer coins there are, the more difficult it is to obtain, which makes them even more valuable. When the figure of 21 million is reached, no more can be obtained and this will increase its value. Currently, 12.5 BTC is obtained for each block mined, but, the automatic difficulty setting established by Nakamoto, states that every 210.000 blocks, the reward is reduced by half. The next reward reduction will be in two years, in June 2020, based on the current hashrate, reducing the reward to 6.5 BTC per block.

Within the market there are many types of currencies and protocols, counting between these currencies that are launched all at once, all the currencies being in the market, so they become a circulating asset, with a known limit and the value depends on the acceptance. The most important examples in the market are Ripple, IOTA, Cardano, NEO or Stratis.

Some skeptics have proposed a possible increase in the supply of Bitcoin, increasing the limit to 21 million, performing a 51% increase or Sybil attack, but this is all speculation, as it is not feasible at the moment. Sybil was tested in August 2016 with Krypton, based on the Ethereum blockchain, which has already suffered a 51% attack and there have been no more cases since.