As we all know, the recent 2 months, BTC has risen to $15000 quickly. This never happened is the past. How to explain this phenomenon?There is only so much Bitcoin that will ever exist, every day less and less bitcoins are being mined. Unarguably, bitcoin is very popular, which creates more demand for it. The supply however, is limited. That's were the basic principles of Supply and Demand come on.
You want a bitcoin, I want a bitcoin, and someone else wants a bitcoin, but there is only 1 bitcoin. Which means that in order for you to get that bitcoin you need to pay more than me and the other person that wants a Bitcoin. There is more demand than available supply.