You can start a blog about anything if you want to and not just an specific niche but when it comes to blogging, Being in one niche is the best because people are on your blog for a certain type of info that you have. I think the problem with one specific niche is that you are boxed in one topic and overtime you have blogged about everything in that topic where you have nothing left to talk about.
I would not just write about anything, I would write about a topic that you know a lot about and it’s your number one thing that you know about a lot. But here’s the thing that I mess up on myself and I wish someone told me about this a long time ago. So lets say you trying to pick a topic, lets try fishing for this example, instead of blogging about one type of fish, you can blog about everything about fishing.
You can talk about all the types of fish, all types of fishing equipment, how to fish and the best time to fish. Hunting would be better because you can talk all about fishing and hurting as well so maybe learn to hunt, just so you can talk about both topic, you would make a hurting blog and YouTube.
This way you have a lot of different things to talk about and you are not boxed in one topic. If you know a lot about the stock market, in instead of writing a blog about the stock market, I would write about wealth or things about money or how to make money. This way you don’t box yourself in just talk about the stock market and you can talk about other things.
On this blog, I write about how to make money online but also how to make passive income too, so I can talk about my stocks, any real estate that I have and anything that has to deal with making money online or passive income.