3080 Tis are closely related to 3090s, but apart from (slightly) fewer SMs / tensor and CUDA cores there's also the 12 GB vs 24 GB issue - and the LHR. The fact that a day after release, custom model-to-model (3080 Ti vs 3090) comparisons show that scalpers are asking up to US$ 2000 less for the equivalent 3080 Ti custom model (so everything else being equal) underscores the 'mining premium' is quite sizable - no surprise there. Non-LHR cards might even pick up in the used market because of this. That said, mining at the broadest scale looks to be subsiding a bit for a variety of reasons, including what could be termed competition from 'govcoins'., environmental regs et al.
For 'normal' / non-productivity use, the 3080 Ti makes more sense than a 3090, though far less $ense than a 3080, what with only 2 GB more VRAM - all this is of course is set in the caveat that most 3080-and-up Amperes (and AMD equivalents) are hard to find in the first place. Still, things might improve a bit if the mining component can be isolated out of the normal demand-supply market environment....or may be that's just wishful thinking...
...but I hope not. I am involved in management of two computer-related firms and while the commercial server side is a different market, the design and staging part of the office is squarely centered on workstations and pro-sumer models. From that perspective, a 3090 w/ 24 GB VRAM is a good deal compared to Quadros, depending on the exact applications and validation requirements. Typically, we're looking at an upgrade cycle of between two to three years - the problem is of course trying to upgrade for business in this crazy GPU (and earlier even CPU) market.
Still, I was lucky to find several AM4 16C CPUs at MSRP a few months back...and also a 3090 Strix OC, again at MSRP (before MSRP went up...). Same place we got all those also had a Radeon 6900 XT at MSRP (3x 8 Pin custom PCB) yesterday, so that was the last piece we needed for this upgrade cycle. The temptation to just buy at scalper prices was of course there, but I/we refuse to reward scalpers, and we had enough intermediate models (several 2080 Tis) to get us by, though everything in this new cycle has to have at least 16 GB of VRAM. I never fully bought in to the 'just-in-time-inventory' approach when it gets to critical inputs for your capital stock.
In short, it can be frustrating when trying to buy a new high-end GPU for your gaming rig, but even more so, if you are trying to buy several for work, or for work-play hybrid functions. While we also purchase from Newegg, Amazon etc, we have a very good relationship with a local outlet of a national chain...as mentioned elsewhere, NONE of the latest high-end CPU and GPU upgrades were ever listed at their national online site because it was just a trickle of supply. Still, I had 'lightning strike' 4 or 5 times now at the same place...so the point is to keep your cool' re. scalper prices and just do the physical grazing of local outlets. I am certain this approach will also work for a 3080 Ti...