In less than three months there will be the third halving in history for Bitcoin.
It is the halving of rewards for each mined block.
The first two halving were definitely positive, however there are also problems to consider.

First of all some numbers:

1) Total Bitcoins to ever be produced: 21,000,000
2) Percentage of total Bitcoins mined: 85%
3) Total Bitcoins left to mine: 2,761,663
4) Total Bitcoins left to mine until next blockhalf: 136.663
5) Bitcoins generated per day: 1,800
6) Total blocks: 619.067
7) Blocks until mining reward is halved: 10,933
8) Total number of block reward halvings: 2
9) Approximate block generation time: 10 minutes
10) Approximate blocks generated per day: 144
11) Difficulty: 15,486,913,440,293
12) Hash rate: 102.53 Exahashes/s

Positive Aspects
-Past: Bitcoin following Halving has had crazy increases going from 12 dollars (28 November 2012) to 1000 dollars (December 2013) and 650 dollars (9 July 2016) to 20,000 dollars (December 2017).
-Rarity: Bitcoin runs out over time, this guarantees its rarity and therefore any increases.
-Bitcoin Request: the past pushes investors to buy, even rarity has the same effect (because the asset starts to run low).

Negative Aspects
Halving halves the rewards for each mined block and the difficulty of mining increases. Will miners still have advantages in doing this?
The rewards will go to zero over time so that it is still advantageous to mine ... fees will increase.
Fees and transaction confirmations will be the miners' only gain.

There are other problems that have not been highlighted in the graph as they are not related to Halving:
-Tulip Trust (they are the first mined Bitcoins, about 80. This is the genesis block momentarily "frozen". If the creator of Bitcoin unlocks these and sells them the market price could collapse)
- Tax regularizations
- Any Hacker attacks
- Pollution (deriving from the proof of work blockchain)

What do you think? You will invest? Will you sell?