Pre-64's, good as they are, are one of the most over rated and over valued guns out there. The reality doesn't live up to the hype. The main thing pre-64 M70's have going for them is it's a finite set. They don't make them any more. The truth is a typical pre-64 M70 is more legend than reality. In most case once you put nostalgia aside and view them objectively most of them are nothing more than good-excellent rifles. A lot of modern rifles you can buy from any big box sporting goods store are just as good. The new guns don't have the panache of a pre-64 but panache doesn't put game on the ground.
To be clear I'm not knocking pre-64 M70's. I'd like to have one because they're pretty cool old rifles but I'm being pragmatic about it. Other than being old there's nothing particularly good or bad about them. I don't think they're good enough rifles to justify the prices they're fetching but value isn't strictly about usefulness. Nostalgia and availability affect the cost too. I don't think pre-64's are worth the premium price but other folks certainly feel differently and that's cool. We're allowed to have differing opinions. YMMV.
Bonk, I'd say you're comments are missing context. Maybe you're not a guy that invests in things that last (rolex, persian rugs, fine guns, 1960s survivor class muscle cars, antique furniture, fine art) so that preference can often cause a lack of enthusiasm for pre-64s. I don't care what something costs, as long as it doesn't depreciate in value. Hence, I own vintage guns but I don't own a boat. But anyway, that's a mentality difference that causes some people to think differently about a boss, purdey, dickson, or even a lowly Winchester compared to a carbon fiber technological gun of today.
Is a pre-64 model 70, new in box, with the original hang tags, in 7x57 Mauser or 9mm argentine worth $12,000-$25,000? Heck, I don't know. They made a handful and they are purely a rare collectible. That said, there is a bidding war when they come to auction.
Is a pre-64 model 70, lightly used, with a lyman sight added, and a G&H side-mount, in .270, .30-06, or 300H&H (three most common calibers) worth the $800-$1200 as a "ruined, no longer collectible"? It's a hell of a lot of gun for the amount of cash they command. A hundred times better than the very best $4000 plastic gun on the Cabelas rack at least. Significantly better than any post-mauser weatherby or post '74 browning. A few reasons: 1.) They are incredibly high quality, they cannot go down in value because the action, the stock, and the sights could be parted out for what you paid for the gun. 2.) They will still shoot exceptionally in 30 years, whereas the $4000-$12000 plastic gun we honestly have no idea if the resins bonding that carbon barrel, or the polymers in the stock, or the sealant preventing oxidization (expansion/cracking) of the metal supports inside the polymer pieces will hold up for decades. 3.) They were made before lawyers existed apparently because they can be adjusted simply to be incredibly precise shooting guns without dropping in an aftermarket trigger.
Lastly, there is the intrinsic value in a pre-64 Model 70 versus a new gun? The pre64 was made to the highest quality at a monetary loss to John Olin when new. Virgin black walnut forests still existed to provide timber you cannot duplicate at production levels today. Quality control was exceptional. Their reputation for 1MOA to 1.5MOA accuracy historically was also not correct, it was true with the crap ammo that existed in that era. I'm aware of many pre-64s that were sampled with a dozen premium factory loads of today that produced 1/2 to 5/8" groups at 100 yards and were sub-MOA at 300 yards. In twenty years when you hand down an $8000 gunwerks gun made by a CNC machine to your heirs, they'll toss it in the trash or pawn it away for pennies as it will be technologically obsolete and it has no intrinsic worth that cannot be displaced by a newer, better CNC in the future. But a pre-64 made by the best American Steel (doesn't exist) with the best American Wood (virtually gone) with American Skilled Artisans (all dead)? Even if monetarily worthless, it will be less likely to be dumped at a yard sale by an heir in twenty years than anything on a Cabelas rack today at any price. I'd say that is evidence at face value that the pre-64 is obviously worth something more than a modern arm.