1 in 100 is ridiculously overstating the serious risks, borderlining on misinformation. You are not doing the same thing with measles parties at all

Here are the risks of the mmr vaccine

Death: literally 1 in a million. These are typically due to anaphylaxis. In much rarer cases underlying immune disorders are triggered, underlying neurological conditions such as encephalitis are triggered, or very severe thrombocytopenia occurs. The majority of cases of thrombocytopenia induced by the vaccine (which is still astoundingly rare) are not nearly this severe and are correctable

Anaphylaxis: literally 1 in a million

Febrile seizures: between 1 in 3000 and 1 in 4000

Thrombocytopenia, a low platelet count: 1 in 40,000. Again, most cases are not fatal

Mild swelling of the glands similar to mumps: 1 in 1000

Mild side effects like rash or fever though? About 5%

Now to contrast:

If you catch measles you have about a 1 in 1000 chance of dying. This is in America, the risk is higher in less developed countries and countries where vaccinations rates are lower (and thus pockets of America where vaccination rates are low may see higher death rates). This is because of the potential risk of developing pneumonia and encephalitis

People who are anti vaccination do not understand medicine at all and do understand the most basic statistics. The fact of the matter is vaccines can and do cause harm. There is no getting around that fact. But the chance of you encountering the harm from vaccines is astronomically lower than the risk of of encountering harm from the diseases they are protecting you from.

To put it quite simply: if you vaccinate your child with the mmr vaccine they have a 1 in a million chance of dying. If you do not and they catch measles they have a 1 in a thousand chance of dying. If you purposely infect them with measles you should be charged with child abuse.