I'm saying that there's a lot of reasons that someone might respond badly to being told that the problem is racism. One is that the problem genuinely might not be racism, as I've tried to say earlier in this thread. Another is that systemic racism is a society-wide thing, and so by blaming a problem on it you indirectly blame the person you're talking to. (or at least they perceive it as such, even though systemic racism is supposed to be the idea that the system can be racist despite the individuals not being racist) A third is pattern-matching past instances of people saying "the problem is racism" to unpleasant/ineffective outcomes for them - for instance, implicit bias training (which while IIRC there is evidence in favor of implicit bias being a thing, training actually working to reduce it is on far shakier foundations). I'm sure there are more, and not all of them are "racist conservative refuses to accept racism is the problem because they don't benefit from solving racism".

On the other hand, "the problem is racism" is very morally easy/acceptable in leftish circles, and saying the problem is anything else often gets a negative response (this thread existing might be counted as evidence here) - providing motivation to call things racism regardless of the truth of the matter... (This is not necessarily the case, of course - just trying to show that motivated reasoning goes both ways)

But the guy in original story I responded to had one specific concrete reason - if it is racism then solution does not help me. And I was supposed to find that understandable.

I was respousing to that particular logic of that particular guy who was much less reasonable then he believed himself. I was not responding to all the possible reasons of all the people in the world.