Well. The 5090ti is significantly faster than a 1080ti. It has 92b vs 12b transistors. That's the 10 years difference you mention. 10 years before the 1080ti we had the 8800 ultra with 600m transistors. So yeah you are a bit right. But stacked transistors in the future might become reality and enable transistor increase again.
A 5090 is more than twice as expensive as a 1080 Ti in real MSRP terms and way more than that in actual real terms, since the 1080 Ti was available for some time below MSRP, while the 5090 realistically never was and usually goes for 50-100% above MSRP. So I don't think these can be compared. Basically a similar story with the 5080, it's significantly more expensive in real terms (and about ~2x in nominal terms).
The 5070 Ti would be the same spot.
If you compare these - the RTX 50 card has a bit higher TDP (which it will usually not reach due to clock limits), is a roughly 100mm² smaller die with around 4x the transistors and about 3x the compute (since much more of the chip is disabled compared to the 1080 Ti's chip). It has 5 GB more memory (11->16) and a lot more bandwidth.