The thing you have to consider is that there are no guarantees for any of us, whatever our age, in this business. If you can accept that then go for it. You are obviously less likely to wind up with a widebody command than someone starting out aged 20, but I know several people who came into commercial aviation at your age and are now happily flying turboprops and smaller jets (eg Dash 8/737/320). It is a risk, but most things in life are about calculated risk aren't they?