That makes no sense. You are unhappy that other people can get something for free now? That's self-centered. You were willing to pay the price, why does the ability of other people to now get the same thing for free change your original assessment? It doesn't seem to change anything for me.
The argument that it was only $5 is a fine one, but to argue the overall point, I'm afraid you're wrong.
Would you feel the same way if you were renting a house, and had been saving away money for years, so decided to buy it off your landlord so that you would be a homeowner rather than renting all your life. Then a week later the same landlord, who owns all the houses on the street, decides to give the houses away to the tenants. Are you seriously going to be sat there, having spent six figures on the house, and say "I was willing to pay the price, I don't care about them now being given away free"?
Even on a less extreme example, if you spend $1000 on an iPad, and the next week an iPad 2 is announced and your iPad is in shops for $500, are you seriously not going to think "fuck, wish I waited to buy it"?
Humans are irrational like that but I try to not get annoyed by those kinds of situations. It's meaningless. If anything I would be annoyed at myself for apparently picking the wrong maximum price I was walling to pay.
But that makes no sense! The time component is kinda important, you can’t just remove it.
I’m not crying over the purchase of my 64MB, 350MHz and 4GB PC in 1998 because if I were to remove the time component the price I paid for it was way, way, way too high. That’s absurd, you don’t do that.
The regret is because your purchasing decision would have been different if you had more information. In the case of "tomorrow it's free", the information is temporal (tomorrow's price) instead of spatial (the other store has a better price).
The amount of regret changes with the time span, largely because of the utility you gain in the interim, but the key is the incomplete information - if you had perfect knowledge, would you still make the same decision?
If you knew in 1998 that 10 years later, your computer would be virtually worthless, would you still have bought it? Sure. In fact, you did know the value would approach zero over time, so there's little need for regret beyond nostalgia.
if you paid $5 for a pencil, to be told a few days later that the same pencil was being offered freely, would wish you had waited for the free pencil?