There are more and more people interested in cryptocurrencies, but in the other hand there are less and less mining reward. The demand is growing so much faster than the supply.
Imagine 21,000,000 Bitcoins for 8,000,000,000 inhabitants on earth.
At the moment, there are around 16,000,000 Bitcoins ; around 1 Bitcoin for 500 inhabitants on earth.
As demand is growing, the value each inhabitant is ready to put in bitcoin will increase, so 1 Bitcoin will represent the working load of 500 inhabitants in a year. Is it much ! Yes it is.