What's the worst possible scenario?

A friend of mine just lost his passport showing it to so many interviewers.

He's gonna get a new 1 and let them know that the previous is missing

My question is, since his pops is trying to instill fear in him and I'm curious myself as to what would happen, is just what the title says:

What's the worst possible scenario?

My own pops says if someone were to have your passport, they could rack a serious amount of $$ on you, with CC companies thinking it's you. My thing is, how they would be able to obtain it (your account #s) seeing as they wouldn't look like you or have any other information aside from your PP #?

Even if they were, say, take a vacation on your behalf, wouldn't there be red flags in terms of information that doesn't match?

Signed,
A curious youngin

If someone found his passport they might get away with putting another photo in his place. Worst case scenario? Someone uses it to get a "replacement" Social Security card and if he ever becomes disabled and needs SSD he has a hard time getting benefits or has trouble getting them to send them to the right address. Someone who's a bad driver uses it as I.D. to get a new driver's license and HE gets mailed the court appearance orders. He gets summoned for jury duty for a county he doesn't live in, etc. etc. etc. These are unlikely things that might happen if it's been to long between when he knew where his passport was and when he got the replacement.

yeah, he already sent out the form for lost or stolen passports,

And here I was thinking that your SS Card was your most prized possession

Thanks

the passport cannot be used for very much other than travel and general ID. and since anyone else wouldnt match the photo/description, its not of much use to anyone else. modern passports are pretty much tamper-evident, so exchanging the photo isnt an option. to get a new dl, you need multiple form of id. and getting a new ss card is more difficult than one would think, I've had to do it a couple times.