I know a couple guys that cut wood all year, I also have cut a lot over the years as my parents utilize an outdoor boiler and heat a big house and garage with it-they burn a lot of wood.
You're basically working for 10-12 bucks an hour once you factor in gas, maintenance fees and all other overhead, plus buying or hauling the wood. It is a bunch of work, but can help you keep in shape, and if you have machinery and enjoy it, why the hell not.
If you want to make better money and don't mind sitting on wood, hold the wood until late winter and hope for a ton of snow and cold-when supply runs out, demand goes up, so can the prices.
You need a splitter and a couple saws, learn to sharpen on your own. You need a wood yard-place to cut, stack and store wood all summer. All the serious cutters get the wood delivered by semi in the summer and cut/stack to have ready for the fall/winter. Some have bought dump trailers, tractors, the whole deal, even a splitter/conveyor, really impressive stuff.
If you want to make better money, focus on the per bundle summertime/seasonal traffic. I know a guy that owns a route and has made some serious cash with the route. Think campgrounds, businesses, roadside pickups.
Most guys do it for a few years then quit when they realize how much labor it is and how little money there is in it.