Dude, I love the analogy, it's appropriate and vivid, and because I once got demolished in Quora for making a question about vaccines assuming they contained "small doses of the virus," let me get you out of this one 😂

What vaccines contain is an atrophied or dormant version of the virus. Not smaller, but weaker, so our immune system can handle it better.

Which only causes your argument to make even more sense because those "small" challenges we set to overcome fear are as big as we can take them. Except they are innocuous enough that, should they go wrong, we would still come out alive. And that's what makes them manageable enough for us to endure them.

But all things considered: great job mate.