There's plenty of CPLs and ATPLs who have both applied for ATC and made it (along with plenty who did not get accepted and/or did not make it through training, as with any other applicant background). Having some professional aviation background can be a help in some ways. Once in ATC, people tend to stay in unless they are found to be not up to scratch performance-wise (typically at-fault incidents or a poor check performance history), or self select back out for any number of personal reasons. If you decide to go ahead, a sense of commitment is an important factor for success. Do your research. Keep an eye on the website for when application windows open.