Yes, that is a very important question.
For ages I didn't see the what is the sense in it, if the CTR (click through rate) has an average of 0.03%, but now I know. And here I tell you.
The 0.03% of the users can be reached while they are working on their office computer. So this is - most probably - the highest income group of people. I mean highest income large group of people.
Linkedin tells us to use the other 3 (was talking about last week [11/26/2016 InMail] and will talking about next week [Sponsored Content] and the week after [Direct Sponsored Content]) advertising platforms.
As you know we can not really figure out where did our buyer get the impression made her/him to purchase at us. The funnel is large, and the most people you reach your customer, the better chance you have to grab them.
4 of 5 users - according to Linkedin - are decision makers.
And for sure there are many who are influencers, influencing decision makers what to decide.
And they mostly work in front of a desktop,or a laptop.
And you shouldn't forget about the landing page. You should have specialised landing pages for every channel, so you can see where they are coming from.
Don't forget to USE A/B TESTING, and test everything you can.
Change currency to USD and pay same amount as you would pay in EUR, so you gain a little ;)
And measure as well. AssLinkedin CEO) said, what you measure, you can correct...
If you want to advertise in any other than the 24* supported languages, you can hack Linkedin in 3 ways.
Arabic, Bhasa Indonesian, Bhasa Malaysian, Chinese (Simplified or Traditional), Czech, Danish, Dutch, English, French, German, Italian, Japanese, Korean, Norvegian, Polish, Portugese, Romanian, Russian, Spanish, Swedish, Tagalog, Thai, Turkish