I personally think the question should really be "Is it worth it to you?" Much like some people love buying expensive watches and others prefer bargain basement ones everyone is very different and will only spend what they are comfortable with.
For the record I have clones, inexpensive authentic products as well as some very expensive high-end gear. In my opinion people should use what they like and what they can justify to themselves in terms of cost because whatever you use is keeping you off the fags so its technically all worth it!
We have seen a shift in the last few months with many of the notable clone companies producing their own authentic gear at very affordable prices. I am thinking of products like the Billow V2, the Freakshow Mini and the Sapor. I think its a good thing they have done this because there will always be a market for inexpensive gear and it means they aren't ripping off small companies and stealing their designs when they are fully capable of contributing their own.
As to whether high-end gear is worth it you have to remember the price often reflects small or one man manufacturers that often have small production runs with expensive costs so while the prices may often look like a complete "rip off" they aren't really making as huge a profit as you might think.
Having said that I own a Rose V2 Clone and an authentic Rose V2-S, the vape is comparably very similar. The difference is really one of build quality. The clone has really shite screws and the threads are nothing like the ones on the authentic which fits together beautifully which is what you would expect for a tank that costs over £100. The airflow control on the clone is prone to sticking a lot and locking in place whereas the original is perfect. The ceramic cup on my clone is without the issues previously described but it is a little loose compared to the authentic.
Do I regret buying the authentic? Hell no its a bloody great product but would I have spent that amount of money if I hadn't tried the clone? Possibly but not definitely because I wouldn't want to buy something that expensive blind without a certain amount of research. The real problem exists that unless you can try some of this very expensive stuff out you have no idea of whether it will be worth the price tag so a clone can be useful at times.
The only problem is when the clone contains a flaw that isn't present in the original and you end up judging the expensive product without ever trying it for yourself.
Anyway at the end of the day you can all buy what you want if it makes you happy.