Being young is, fortunately, a curable problem (but one I wish I still had). There isn't much you can do about it in the short term. Face it, it makes you unusual in the context of RTW trips in F. Unusual gets reactions from these folks. It's what they're trained to look for.

You might say you were lucky enough to get into a dot-com early and get your money out before everything tanked, so now you're enjoying yourself for a while. That's consistent with your age and the situation. Other than that, as others have suggested, stay calm and let them do their thing. They can make things more unpleasant for you than you can for them.