⭐ Merited by The Pharmacist (5)
It says that there will only ever be 21 million Bitcoin and the current BTC supply is almost at 19,094,150. What happens when its limit reached? will BTC price goes up instantly due to scarcity? is it the doom for Bitcoin since there is no room to mine? or maybe it will likely never reach 21 million?
As I got from bitcoin.com, the Bitcoin network's inflation rate per year is 1.74 percent and after each halving process, the annual inflation metric will continue to fall.With the halving process, it can be said that the mining process will run slower.
BTC is last expected to be mined in 2140 or about 118 more years meaning that over the past 13 years since the start of Bitcoin, miners have earned 19 million BTC as already mentioned by Apocollapse.
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Correct, Bitcoin supply will never reach 21 million, but it's almost closest to 21 million on 2140 
If Bitcoin is scarce, then the price will be very high. So when the current price of Bitcoin is still at the point of $21K and at the price of $18K, don't panic.Please read the two references below for easy understanding.
Link 1
Link 2