After age 30, people tend to lose lean tissue. Your muscles, liver, kidney, and other organs may lose some of their cells. This process of muscle loss is called atrophy. Bones may lose some of their minerals and become less dense (a condition called osteopenia in the early stages and osteoporosis in the later stages).
But im not saying that it's impossible for you to become pro, just less realistic. Remember that nothing is impossible, also if you lived a healthy life and your body feel good then you also have better chanses, your 30+ body could be just as good as someone that is 20. ALso never listen to what other people says and always believe in yourself. If you're even thinking of becoming a pro i would say try to work on your intellect and be an igl. You can do it.