I agree with most posters - you might make a profit, but it will not likely come easily.
We have 90 acres of rolling foothills - some wooded. It is fenced into several smaller areas. From time to time I need to walk the perimeter fence line and lugging the wire, posts, post pounder, cutters, and sometimes a chain saw. That can be a real PITA..
Worse is getting a call from a neighbor who has 100 acres and tells you that your cows are on his property. Then you have to hike up and down hills to find where they got through, find the cows and herd them back to the hole in your fence - not so easy to herd cows up and down hills in the woods. And you cannot always find them - and you don't even know for sure how many got through.
Worse than that, once we received a call from a neighbor who told us that 5 of our cows were out on the highway. We were 6 hours away by car from home. Panic time. I had to cut our vacation short - jumped in the car, and called a friend to ask for help. He recruited another guy and managed - after a lot of effort - to find the cows - and managed to get them back to our property. Later I found that a large tree branch took out a section of fencing.
Anyway, we never made any money - but had cows because they kept the grass-pasture grazed down which made it less risky for wild fires (Central California) - and with the right size herd and enough grazing, expenses were not great. And we had a lot of stories to share with admiring city folk.
I did enjoy, when the kids were young, having cows, seeing the new calves, and such, but I no longer want to fix the fences, buy and sell and transport cows, lose a few, castrate a few, vet issues and all that. So, now I lease the pasture to someone else. He pays me only $800 a year, but he has insurance coverage, and he is required to inspect and maintain all of the perimeter fencing. We still have about 8 acres inside of the 90 acres fenced for our own use so we can have a couple of cows if we want, or to raise our own beef.
Oh, I don't think anyone has mentioned the fly problem. If the cows can graze near your house, you will need to deal with that as well at certain times of the year.