Ok, chuck53 is right don't take my advice, I'm just the same age as these guys and doing what they want to do.
All I'm really saying is take some chances, it's better to be "young, dumb and sailing, than old grey and failing"
OK, let's back up. No where did I suggest that they shouldn't follow their dream. All I'm suggesting is a pathway to achieve it.
These guys are looking at 29 months until they buy a boat and sail the islands.
29 Months! That's plenty of time to buy a sailing dinghy to get some time on the water. Maybe take a few classes. possibly spend some time on other people's larger boats. And since boating classes aren't always just for newbies, they just might meet some nice sailors willing to take them on their boats.
29 months to learn and get good experience that will make their adventure even more memorable and maybe safer.