Losing just one loaded variable GC can happen to anyone and it's not about being smart or dumb. One can try their best to be organized but sometimes, Murphy's law takes over and you lose one, sometimes more. We need presence of mind when draining lots of these at one time so if one is extra cautious, they can take a pic of their VGCs front and back just in case they lose it, they will be able to report it lost/stolen and ask for replacement. Inconvinient? Absolutely! but you'll never know its value until you lose one, two or more! Not knowing vital info on the card, it is definitely lost because they're like cash. Anyone who picks it up especially the GCM cards that say card is active (or GCcom activated cards) can easily find out balance of card, process it as credit and wipe out the balance in minutes. They don't even need the PIN to wipe out the balance buying goods.
It is really up to each individual to know their strengths/weaknesses/capabilities for them to decide the level of MS they'll do, if at all. We can't blame others if we can't do it right, we alone, are fully responsible no matter what.