I am currently a history major and lover of video games. I want to combine the two because the video game industry is twice the size of the music industry. I was just curious if this is something I should pursue or just write a book about later.

You can combine the two, but you do that because of love for it not because video game industry is two times larger of music industry, because video game industry being larger than music industry doesn't mean you are going to make it. In my opinion go for the video game niche base on the love for the video game market so that when you face challenge in the industry you will be able to endure, sustain and  can over come it. In video game industry there are sub niches in it, writing book is just one of the niches in the video game industry.