There are plenty of people who make a living on cattle, but you won't find many with the time or the inclination to post here. It seems like most of the people with the time to post on this site don't live in cattle country so I am not surprised that they don't personally know full time producers.
It is still possible to make a living with cattle, but it does depend on where you live. In the Umpqua Valley of Oregon you can still find reasonable land to lease, but you will need to have lived her much of your life to have the connections to find it. Off the top of my head, I can think of 8 full time cow/calf operations and one stocker grower who are personal friends and have no income outside of the ranch. You won't find any of them posting here. They don't have that much spare time and most cattle questions they have can be better answered by a fellow rancher. My husband and I are retired from other occupations and run about 50 registered Angus cows on 1000 acres. We make a profit, but not enough to support our lifestyle. I would need up to 10 times as many cows for that, thousands more acres and it would mean working long hours. We do it because we enjoy it and it brings in a little extra income but we don't depend on it as our primary income.
The full time ranchers I am thinking of range in age from their early 30's to 80+. There are many more where a spouse works at least part time to pay for health insurance. Some of these operations support three or more generations and some are on their own. Some have land that has been in the family for years and others lease almost all. Most started out by working at and eventually managing another ranch in their youth and eventually saved enough to go out on their own. I would say 400 cows would be the minimum to support a small family. In this area, many also run sheep. Some retain ownership to harvest and others sell at weaning. About half of those I know are involved in some direct marketing and some also have diversified to bring in hunters who pay for the privilege of trespass. All of the ones I know, either own or lease a minimum of several thousand acres. Irrigated land is scarce and will run more cattle, but most of this land can support less than 1 pair on 10 or more acres. The stocker grower runs as many as 10,000 animals in 4 states on over 100,000 mostly leased acres. While buying stockers in the Fall or winter and grazing them to about 800 pounds is his main operation, he does also run a few hundred pairs. When prices are good many will buy more land. Wealthy city dwellers investing in rural acreage have made this more difficult in recent years. They will pay much more than what the land is capable of generating in income. Fortunately they will often lease this land out for a fraction of its worth in order to keep their AG credit for real estate taxes.