There's less room for the same argument with small pox. In fact small pox is where the term vaccine comes from - it was observed that milk maids weren't getting smallpox, which led to the discovery that infection with cow pox (which is relatively harmless) provided immunity to small pox - hence 'vacca cine', vacca = cow in latin.

But there's a long history of people trying to self vaccinate with all sorts of things against small pox including using scrapings off somebody's small pox wounds to hopefully give oneself a light infection. Needless to say that came with well understood side effects up to and including full-on small pox infection. But when the death rate is 30%, people were willing to do some crazy things, because the risk:reward was seen as worth it.

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FWIW I did ultimately decide to vaccinate my children against measels, but it was not an easy decision, because it is in general not that risky a disease whose mortality rate had already precipitously declined (from 13 per 100k to 0.19 per 100k) [1] before a vaccine was first introduced in 1963. Obviously I think it's the right decision, but I also wouldn't really fault anybody for going the other direction either.

[1] - https://ourworldindata.org/grapher/measles-cases-and-death-r...