Your coworker is an idiot. Everyone start somewhere, and has their own goals for what they want to get out of cycling. I met a guy on yesterday who was 67. He has only been cycling for 2 years, and went out and bought a Willier Gran Turismo. Way more bike than he needs, and he fully admitted it. He said if he is gonna be slow, might as well be on a nice looking bike. He can afford it, it gets him riding, and it's helping his health (he was rather overweight). Who cares if he will never realize the bike's potential?

I say good for you!