If that is accurate reflection of the true drop rate, then it is roughly 0.4% success rate and 99.6% failure rate. One would expect ~1.6% of the time to go1,000 consecutive chaos runs without a HR.
Simply put, D4 should not be designed to be a grind fest but to be more friendly to someone who invests hundred but not thousands of hours.
I played both D2 and D3 thousands of hours that is not who the game should be designed for.