As we all know BITCOIN mining will stop once the 21 million mark is reached. According to the information we have 19 millions coins were mined and now circulating. The remaining balance is about 2 millions to be mined. Why it is not possible to mine the remaining BITCOINS before 2140 when the 19 millions mined in just over 10 years?
Mining won't stop when all bitcoins are discovered and mined. These "miners" facilitate transactions as well and the fees we pay the network actually goes to their pockets, so with that being said the mining industry won't necessarily go out of business when all bitcoins are mined. They'd just be redirecting their focus on something else.
As for why it's going to take time before all bitcoins are mined, one thing that you have to keep in mind is that the difficulty for earning bitcoins through mining isn't linear. It's exponential. What took a few minutes/hours for people back in 2011, is now taking weeks and months for powerful asic miners of this day, I don't wanna delve into the maths of it and the complicated tech jargon but basically picture this:
You have the whole planet (internet) to mine gold on (bitcoin), as more and more gold are mined from the land, the less the supply is, and the harder it becomes to mine and earn the remaining gold in the Earth cause the area you have to work with didn't get smaller as you're mining more gold, it became bigger and thus more land (blocks) must be mined in order to find gold. That is basically how it works for the bitcoin mining industry.