1) Hopefully nothing goes wrong on your trip and you don't have to fly back to the US from a foreign port.
2) Please be aware that you may still be required to present a passport to enter the countries your cruise ship is visiting.
3) A person can afford a cruise but can't afford a passport???
I have been to literally every western carribean, eastern, the bahamas, and the caymans, as well as mexico. They only need to see your cruise key at the ports.
Yes, if something happens, like you being irresponsible and missing your boat, will put you in a bind for a few days. If an emergency occurs, we wouldnt knowni anyway. That is the time that we completely detach from the outside world and be a family. The only time these days.
Its not about being able to afford it. I can "afford" to burn $125 right now just for fun. It doesn't make it a good use of my money. You can go on a cruise for about $250-$300 per person. A passport is $125 or so if I remember correctly. Why pay 50% more for no reason? If you are afraid youll miss the boat, buy one. If you are afraid something might happen back home, buy one. For us, it makes way more sense to spend that money on the ship or an island, rather than on paperwork we dont need.