But according to Google, you can see that "Instagram" is the most searched topic in the past 5 years.
And this is Bitcoin's
https://www.google.com/trends/explore?q=Bitcoin
Since bitcoins are currently used some % of people in the world, and it will become hot topic only if any significant good or bad news comes out on bitcoins or related to its transactions otherwise I don't think it will be a hot topic. At least in my surroundings many people don't anything about bitcoins, it will become popular only if it is accepted in any mainstream business.
The hot topic so far is always the bad news. It is like media, government and people against it are rejoicing whenever something bad came up. They dont know they are helping in advertising bitcoin and putting a question in some people mind. "What the heck is bitcoin?" Then there you go another bitcoin user is born.