I would not say that flying a Heli is harder than a plane.
You just have a different set of procedures and skill sets you need to learn.

Now the cost of the two depends on what your flying, and needless to say, the wife was glad to see me buy a plane instead of another heli.
When I went to the local Airplane field, I seen two guys flying some kind of competition pattern planes with 2 cylinder gas motors.
I was very impressed with their flying skills.

My goal is to be able to one day build and fly a Sig Four Star 60.

Rick