It's an unfortunate character flaw.
Which one? Being trigger happy at throwing insults, or being a hoarder? I'd consider both equally bad, but I mean, you know what you're doing when you go in spending a ton of money on prototypes, and the hassle and flack that might be involved when you keep said unreleased title for yourself. You cant just jump in some close knit community, say "hey look what I got, here is two screen shots" then blow everyone off for weeks on end, then come back and lay blame down on others as to the reasons behind your absence and think no ones going to smack you down. It's in poor form. You're the one with the prototype, any "sharing" of said game kinda falls on you since you decided to take up the responsibility for the titles safe keeping and preservation when you purchased it.
The best way to preserve said game is basically to share it. I know that sucks for your pocket book, but if the sole interest in buying these things is to preserve the work that was done, well, its not going to happen when it just goes for years untouched on a shelf. Dealing with arcade hardware for a decent amount of time, one of the first things that pops into mind is the fact that over time eproms will lose their data. These 20 year old prototypes relying on eproms and all, well, you already know where I am headed with this.
Also, I'd like to mention, and I really don't know if its still the same way now, but it seems like I remember in the arcade community people being more interested in sharing unreleased titles romsets with the entire community instead of simply hoarding them, to make sure a wider audience is available to preserve them. The mentality and goals seemed to differ greatly from the going on's of the prototype business for game consoles, since on the console side typically the potential releaser is only interested in getting their money back first, or in some cases, doesn't care and has no intention of sharing at all what so ever.