This has actually proven to be the case; there are a number of studies on assaults committed against taxi drivers, and all (I've seen) come to the conclusion that males and African-Americans are much more likely to be violent.
It's also pretty rich to have the position that you won't put in the work to back up your statements, but that those who call you out on that should be willing to do the work to disprove you. Just replying to you with "I have seen studies that say the opposite" is equally as (un)convincing as what you've said.
The problem behavior which I have seen cropping up on Hacker News is people asking for citations as a quick and easy way of invalidating other people's views, while justifying downvotes (which have become far too common). I have also observed that many will ask for studies, then either ignore them for viewpoint or ad hominiem reasons, or attempt to invalidate the study by nit-picking. If the original commenter lied or pulled numbers out of thin air, it is fair to call them out (in my view), but laziness on the part of the respondent is no justification for snark.
"Prove 'the state of my knowledge' is wrong."
The burden of proof lies with the original claim maker, not the respondent. This is not a bar room conversation from the 90s, we are literally on the internet; citing one's sources isn't too much to ask.
Do you have a white-list, black-list, or other standard for sources? What type of evidence would satisfy your standards, and what are the minimum sample size, maximum p-value, and robustness with respect to alternate causes? Do you require some amount of replication, peer review, or publication?