It's NOT killing 1% of the people who catch it. It's killing 1% of the people who were sick enough to go to the doctor, get tested and confirmed it was COVID.
The 0.1% fatality rate for flu is an estimate. It's based on an estimated number of total flu infections, and is very soft. There's no testing behind it. The COVID-19 fatality rate being reported is based on positive tests, not on estimated total cases...so it's not a fair and direct comparison.
To illustrate more clearly... CDC estimates a high end estimate of 54 million flu cases in the US this year, 25 million medical visits, 710,000 hospitalizations, and 59,000 deaths. So, if you figure 59,000 deaths divided by an estimate of 54 million cases, that's a mortality rate of 0.1%. That's the number being used, but it's a soft estimate. If you use the number of medical visits instead, mortality rises to 0.236%. And if you use hospitalizations, it rises to a whopping 8.3%.
COVID-19 doesn't have an estimated number of cases or hospitalizations. There are about 68,450 confirmed cases and 1,027 deaths. Most sources say that 80+% of people infected have mild symptoms, so if 68,450 is only 20% of total infections, we're talking somewhere near 350,000 infections. 1,027 deaths in 350,000 infections gives a mortality of 0.29%. Still higher than the flu, but not as alarmingly high.
Bottom line is that the comparison is faulty. For the flu, the lowest possible estimate - deaths per estimated total flu cases (whether the patient went to a doctor or not) is being compared to the deaths per lab confirmed case for COVID. It's not apples to apples, it's more like apples to wingnuts.