How to choose the history dissertation writers for your paper?

I have seen many students choosing history dissertation writers online due to its complication level. Is it really a difficult task? Even recently I saw my friend who was much worried about his dissertation task. Although he was also looking for the best writer, he did not have an idea to find it within his budget. So, can you please guide me more on this so I can help my friend I am sure it will also help me in the future because I am also about to graduate and I know I also have to face this dissertation writing task?