It's actually not even bad lol, people are over reacting.
If you go and look at the price number differences a cheaper GPU is not bad for a 2080ti owner.
The value loss of a 2080ti only matters if you were planning to sell your card and not buy another Nvidia card.
But if you are upgrading then it doesn't matter - yes your 2080ti is worth less but so is its replacement - the net dollar difference you have to pay in to upgrade is much lower than last gen. A 1080ti owner had to sell their card and then add $700usd to get an upgrade, but a 2080ti owner just adds $200 to get an upgrade after selling.
Sure if the RTX3000 were priced higher than RTX2000 then the 2080ti would be worth more but then you would also have more to pay in to get an upgrade.
Let's look at the housing market where this comparison works perfectly as well. Let's say tommorow the whole housing market drops 20% - suddenly everyone who bought in the last year will feel bad, until they realise the price doesn't matter if they are buying in the same market because their next property will be cheaper too.