There is a multitude of reasons why people support abortion. One of the common arguments is that it is better to not exist than to be born poor or to parents that don’t want you (I.e literally the “born to the wrong vagina” argument). This is a widely supported belief and I would say that around 20 percent of pro-choice people I’ve debated (out of hundreds) use it as their primary argument.
Asserting that there is a single reason why people hold a position is absurd.
FYI bodily autonomy arguments have largely been abandoned in academic ethics, because there is just no existing right to bodily autonomy that is sufficiently strong, and we have no basis for arguing that there should be.