[XorNot]

Sort of? But it's less "there is a particle doing things" and more "there's a probability field which can describe a particle doing something" (alongside a bunch of other probabilities it interacts with).

One of the ways you can calculate the probability of nuclear decay for example is to assume that the particle you expect to see is literally existent and trapped inside a potential well defined by the atomic nucleus and then calculate the probability it tunnels out of that to free space.

The thing is "why" does get pretty anthropic: protons match electrons because we observe them to, and then on top of that we observe nuclear decay causing the conversion of a proton to a neutron + a positron (within the limits of our instruments) - so our model predicts that these are in fact the same value, and we keep measuring to check that they converge in that direction (it would be a big deal, for example, if we discovered this wasn't the case - every physicist would love to find out that proton charge and electron charge are actually slightly different).