Getting accepted to present at a conference, but choosing not to go - including this in SoP
It's not unheard of for someone to be unable to attend a conference after having their work accepted. This can happen for any number of reasons that may be seen as having varying levels of validity in someone else's eyes, ranging from "death in the family" to "I have better things to do". I don't see a compelling reason to open yourself up to such value judgments about your reasons for choosing to not go to the conference. Having your work accepted at a conference is an accolade in itself, so it's worth mentioning, but you could simply say that you were "unable to attend" and leave it at that. Your particular reasons for not attending aren't relevant to the point you're making (that your work is good enough to get accepted), and may or may not be viewed unfavorably depending on the individual, so there's not much of a reason to go into the details.