A lot of delta-V.

The only parking orbit is graveyard, above GEO - everything decays over a fairly short time period.

Yep. It would require a ton of money to tank that much fuel up there. For maintenance alone, ISS requires 7 metric tonnes of fuel every year just to stay where it's at.

7 metric tonnes isn't a lot. It's what a 747 uses to taxi to the runway.

Of course bringing 7 tonnes to orbit is another story but even that is not so bad.

I had to look that up. A 747's max fuel capacity was 63,705 US gal according to [https://en.wikipedia.org/wiki/Boeing_747] and jet fuel is around 3.25kg per gallon, so ballpark of 207,000 kg or 207 metric tons could go into the biggest 747s. 7 metric tonnes is about 2,150 gallons.

Interesting stat. Isn't a lot, but it sorta is, too.

The GP's estimate is out by almost an order of magnitude.

"not so bad" is relative: It's two flights of a spacex dragon 2 launcher: 3,307 kg (7,291 lb) to ISS

https://en.wikipedia.org/wiki/SpaceX_Dragon_2

the point is that discarding lumps of metal in space is not wasteful, since it would require much more material brought into orbit to make them useful than to replace them if discarded.

Yeah and they are no longer in a reliable state. Years of radiation embrittlement, holes drilled by careless russians, weakening due to micrometeor impact..

I also would not bother reusing any of it.