There are only two classes of guns, unfired and fired. Once a gun has been fired, the value is what it is. Additional shooting, that does not damage the pistol, does not affect the value.
The Python (and other Colts) good and bad qualities have created legends, and legends get...embellished.
Snake owners are in the same boat as Luger owners now. Sort of. Except there never were $30 Pythons.
Shooting a Python that has already been shot doesn't harm the value. Dragging it through the gravel, scratching up the finish, will. Shooting it to the point of wearing it out or breaking something, will.
Yes, gunsmiths who can do "colt quality" work are about non-existent. From what I hear, Colt can't do "colt quality" work these days.
Guns used in popular movies and TV shows become icons. Icons become religious artifacts, and as everyone knows, religious artifacts are "priceless".
Look at the S&W M29 for one classic example. Before the movie, the big Smith was a slow seller. After Dirty Harry, S&W couldn't make them fast enough. By the mid 70s, with an MSRP of $283.50, there was a two YEAR wait. People were paying $450 to get one NOW.
I watched the price on the Auto Mag creep from $395 up to $995 over about a decade. After Sudden Impact, the price jumped to $1500 within a few months.
The Python (and to a lesser extent) all the colt revolvers are icons, classics, and OUT OF PRODUCTION. Combine this with current high demand because of its use in a popular entertainment show, and prices go crazy, because people with fat wallets WANT them, NOW.
Where were all those people paying thousands to get a Python when Colt dropped production because they weren't making sufficient profit on them???
(a lot of them probably hadn't even been born then...
)
Bottom line, unless it is NIB unfired, if you don't damage it, shooting it doesn't harm the value.