We get asked all the time about profitable niches – and the simple answer to this question is:
Can you provide value to a certain group of people in a market, a group who are willing to spend money on what you offer?
If you can help people get a result that they desire, you can make money in that market.
That's not a question we can answer for you – you need to get out there and talk to people in the market, start helping them, and then use that data to decide whether to build a proper blog business around that subject.
This research process is very important, which is why Yaro has an entire program about it – The Blog Money Finder.
These two blog posts by Yaro should also help you:
and then this one