In the United States, pharma companies make money when insurance companies (and the government, but less so than in many other nations) buy their product to give to patients. In practice, very few people are paying for vaccines out of pocket.
Insurance companies in particular hate, hate, hate giving anybody money for any reason. They will not pay for something unless you beat them over the head with how well it works. And if they don't believe you, they'll do their own analyses. Better to blow a few million on a study than spend a few billion on unnecessary treatments. (This is the same reason that there's a car-insurance funded highway safety institute crash-testing cars.)
And yet, every year, they insist on making the flu and COVID vaccines free and pushing it on as many people as possible! I guarantee you if you call your insurance company and ask if they think you should get a flu or COVID vaccine, or any vaccine, really, they'll say, yes please.
Why would they do that if these vaccines were going to cost them money by a) being useless or b) being harmful? There is simply no incentive!
The reason everybody wants you to get the damn shot is that the shots work, and the downside risks of them are smaller and cheaper than the downside risks of the things they prevent. Capitalism would make it very difficult to repeatedly sell vaccines that don't work, or hurt you; you might get away with it once, but after that, the reward's just not there.
I don't know how one responds to that, if one distrusts vaccines, other than to suggest a much larger and more complex evil conspiracy than is plausible to most people.