Ham is considered to be bad for you because ham is high in sodium, saturated fat and high in cholesterol.
Not only does ham contain lots of sodium, saturated fat and cholesterol but ham also contains some non natural preservatives that can be unhealthy for you.
Ham in moderation though is okay for your health.
Your health is not gonna decline simply by eating some ham every now and then and in moderation ham can be healthy for you.
But if you eat too much ham or other meats including bacon you can increase your risk of heart disease, heart attacks, strokes, blood clots etc.
However just eating ham in moderation is not unhealthy.
It's okay to enjoy some ham every now and then but just don't consume too much ham.
Also make sure to eat other healthy foods and exercise and you should keep your health.