Its a comparison between the money and whatever else is in the equation. Eld gives a good example above. You can replace "money" in this context with pretty much anything. Something you may hear people say is "My health is more of a concern" or "I'm more concerned about my health". Hope this helped :)

It means that the money was important and some decision was dependent on it. For example 'I got a job this summer because money was the concern. More so because last semester I couldn't meet my living expanses.'

usually used in a context where there's a question about whether somethign else is more important right beforehand. For example: Joe lost his shoes, shirt and his wallet, and he was upset, but the money was more of a concern.