Choosing a niche topic may seem like a good idea to start with; after all, originality is key. However, if you start your research and realise that there is not enough literature to support your thesis, that’s a sign that something is wrong. It’s a bad idea to build a dissertation on too narrow a foundation, as the work will likely be patchy and uneven where there are gaps in your research or no available resources, causing the whole thing to come crashing down. Academic sources are essential for any dissertation; this is what the markers will be expecting you to use to back up your arguments; if there are no peer-reviewed academic sources, you are in trouble. However, don’t forget that you can change a wrong dissertation topic!