What happened to bitcoins in 2015?

Delving into the complexities of 2015 in the bitcoin realm, we observe a pivotal year that saw the cryptocurrency undergo significant transformations. The year kicked off with a relatively stable price range, hovering around the $200 mark. However, as the year progressed, the bitcoin market experienced a series of volatile swings, reaching a peak of over $400 in the latter half, yet also enduring sharp drops that left investors jittery. This volatility was attributed to various factors, ranging from regulatory uncertainty to increasing demand and adoption. Additionally, the year marked the emergence of several prominent bitcoin exchanges and wallet providers, furthering the mainstream adoption of the digital currency. Overall, 2015 was a year of both challenges and opportunities for the bitcoin ecosystem, laying the groundwork for its continued growth and evolution." Now, the question arises: "What specific events or factors do you believe had the most significant impact on the price fluctuations of bitcoins in 2015, and how did they shape the market's overall trajectory?