You can compete at a high level as an amateur if you put in hard work and dedication.

To be a professional in any sport requires you to have an extraordinary amount of talent. Sure, hard work can make up for some of it, but hard work will only take you so far. There are plenty of hardworking athletes who are forced to give up on their dream of continuing (or even having) a professional career.

If you start in your mid-twenties, even if you were really talented, you would still have a lot of catching up to do and just a few years to do it in. In short, if you have some kind of prodigy level talent, you could do it. But for us normal folk it is a dream within a dream.