If you love Boxing, then Box. If you want to knock people out for a living, then go Pro. You've actually still got a good amount of time to burn in the Amateurs where it doesn't matter much if you lose, but the experience is more important. You can spend 20-24 in the Amateurs (granted you have talent) and maybe even win a couple Championships somewheres.
Then go Pro, and as long as you don't do stupid shit like yo-yo in weight, drink, beat up women and get thrown in jail, snort coke, etc., take care of your body, train properly to avoid injury, and stay out of trouble, you can have a long and fruitful career.
I train with Mike McCallum, who always laughs at me when I express that I'm old to be beginning (29, started training SERIOUSLY at 26), according to him I'm stupid for worrying about it and have a good 10 years in the game if I do right.