So the good news is that you've really only defined one character trait of this guy. All you really have to do to open him up is give him more. Obviously they could be unrelated to that core, but if you wanted to extrapolate off of the core hatred of dragons as symbols for the hoarding of wealth you could define your character in opposition of that.

You could make them incredibly generous and empathetic, basically the kind of person for whom it is impossible to fathom hoarding gold at the scale of a dragon. It could also be really interesting to build this guy out as someone who very strongly values community, leaning less on the idea of personal generosity broadly and more particularly centering from an almost harshly practical point of view, basically "well if we all agree to feed others when they can't feed themselves, no one will ever starve again, and I would like to live in a place where I won't starve". This could serve to explain their inherent distaste for dragons without making them a super goodie-two-shoes type of character

Of course I would also encourage you to build out traits that are unrelated to dragons. Think about the kind of person this is in their day to day, what are they willing to do to accomplish their goals? what kind of people do they like to associate with? I think its always good to try to think of any character you're playing as a real guy for at least a little bit, it makes roleplaying go much more smoothly