Makes sense if you have $1200 that you're not going to spend on anything else...but seriously, it's hard to answer that question without knowing your financials, knowing what you consider "worth it" (some people spend $50 on a glass of single malt scotch...not worth it to me, might be to you). It is unquestionably faster than 1080ti, how much faster kinda depends on game/application.
In my opinion its not, except you really want it.
the approx 30% gain in performance gain for the double cost of it is, for me at least, not really a must buy.
however, if you need and really want the newest product there is, go for it.
but in terms of bang for the buck , id rather wait a while longer till the prices drop a good amount.
the 1080ti is more than solid for now and a good while longer for even 1440p.
for 4k gaming tho, im not really a fan of it for now, since whatever you put into it is way to costly to be even of a big relevance.
i do think 4k gaming isnt still what it should be.
that sayd, if you go for 4k gaming you would need even more expenses on a whole decend setup
- monitor, strong cpu on a newer chipset like z370 and above.
and even if you already run that, id wait for your wallets sake.
i do own a 1080ti my self that i oc to 2100mhz stable and its more than enough atm for every AAA game that is out right now and to come with some, even using it for the HTC Vive. id rather compromise later on on adjusting the game settings for the upcoming AAA games like metro-last light, cyberpunk and so on, till i really feel a hit that drops me under 60fps and consider than if id be willing to either sell it, or use it for a second rig, and buy a new gpu like the 2080ti.
if you just dont care about your money, go for it. i for my self do really care to get the best out of my cash und invest when i need it and for what i really need, swallowing what i would like to have. since it leaves you the option to upgrade other stuff like an NVME drive and other stuff youd profite more at this time.
may i ask what elst does your rig pack? that could help more further.
If you want to play in 1440p@160hz or 4k@60hz max settings averaging over 60fps then it may be worth it if money isnt an issue. If youre running those monitors then it likely isnt, as they tend to cost a fair bit more for good quality ones.
No real reason if youre playing at 1080p even at 240hz, 1440p 60hz or even 100hz youre also fine without issue. Unless you just want it.
First you need to define worth it. By all logical, rational, and financially sound reasoning, no video card over $200 can ever be worth it. A GTX1060 goes for around $200 and the GTX2080ti is at best 3x the speed and that is probably being generous, so that means a max of $600.
But if you want to have the bragging rights to show off to your brother.... well then... what can anyone say?