Are you being serious? Perhaps you don’t know the difference between need and want? Do I want a Ferrari? Absolutely. Do I need it, of course not. 
It seems to me your need for performance is based on some old school macho world view rather than reason or experience. We are also not talking about entertainment for the programmer. You can’t drive a game engine for fun. It’s a tool to create games and such there are many more considerations, such as productivity, usability and so on.
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I not only want best possible performance. I need that too. And I’m getting it with C++.
What do you mean that you don’t need best possible performance? I simply cannot agree with this.
We are talking about best possible user experience. Games need best possible performance not just “good enough”. C++ provides it. C# does not. It is as simple as that.
Productivity is either identical or better with C++ when you start to either create large code base or use it.
Usability - same.
“So on” category? You simply cannot beat C++ in any field really:
Performance - unmatched
Portability - yes, whilst with C# you get either no or yes, but with very poor results
Level of abstraction - identical to C#
and so on and so on and so on.
Stop fooling yourself. No, seriously, stop.
If you aiming at creating best possible game, you need to get best possible tool not just good enough. C++ is the best possible. C# is not good enough if you are interested in perfection. If you are interested in mediocrity then sure, choose mediocre tool and create mediocre product.
You know, analogies go only so far, and there is no perfect analogy, but, continuing with C++ being Ferrari and C# (and other slo-mo creatures) being ford fiesta, you behave like this guy:
Someone offers him Ferrari for really cheap installments (E20 or S20 if in USA) and what this guy does? He starts complaining. Why? Because learning how to drive fiesta is so much easier than learning to drive Ferrari and guy is simply either too lazy or incapable of doing so.
He starts pointing “faults”:
Driving Ferrari is so dangerous you know guys, it is going so, so fast that you can really hurt yourself you know… And, and, if you not careful… if you not careful then… then you can really hurt yourself… yourself and others too, you know guys, compare this with fiesta and the choice is obvious guys, fiesta, good, safe(ish), no trills and no frills but gets you from A to B so why would I need Ferrari for that?! Give me fiesta, for the same price of course. Not only that guys… my mom told me that Ferrari is so, so much macho car and so, so not sexy anymore that there is simply no need or point in driving it. My aunt on the other hand is convinced that if you can drive your fiesta from her house to the grocery shop and back that is all what you really need from a “motor vehicle”. And she is best my aunt… she is so calm and she wears glasses, really nice glasses, and she talks so slowly, and walks too. She is really nice my aunt. So surely fiesta is better than this flashy Ferrari… Surely guys…
Guys…?
Yep, right… got ya!