Of course in the beginning it is used to buy online product and its value was low but at present it is the most valuable currency on the whole world. Nowadays it is used for online payment, paying the online bills and buy different software, games, webdesigns and websites. It has become so popular that people are using it instead of money and it is called a digital currency.
Initially, bitcoin was not so popular and its value was insignificant but it was treated as a currency to buy online stuff and services. Over the years, bitcoin has gained more trust and popularity and the price of bitcoin has gone from nearly nothing to thousands of dollars' worth nowadays and people have started to use it as an investment rather than a currency. It is still used for online transactions but it seem to be that people are more interested in the profit they could earned from bitcoin investment than in its advantages in online shopping.