Thanks to everyone for the response. But, lets look it this way, when Bitcoin started, there was no other cryptocurrency to trade with it, yet its value increases. Is there any answer to why its value increases then without trading it with another coin?
There was the dollar (and other governmental currencies) to trade it with. At first people weren't willing to spend much money on a digital currency, so Bitcoin was pretty cheap. Then once more people started getting interested in it, price rose due to the rising demand vs a diminishing supply.