It's not the same time. The flu has been with us for ages and it mutates and returns every year slightly different so that's why you need different vaccine every year.
Here's CDC's reports on flu cases this season:
It didn't start at the same time as the COVID-19 virus. By that graphic they started charting it in the 40th week of the year. This is September 23-September 29. In other words it has had 6 months to spread already and at the moment there are 242,330 cases. COVID started spreading in late January and epidemic growth goes by exponential curve. Meaning it jumps disproportionately later in the curve. (you can see the same for the flu, but with not as steep of a curve before it tops out). The US is currently at 143K cases of COVID and it has been spreading for only about 2 months. It probably will surpass the flu by the end of the week and blow it out of the water by the end of the season. And this is with the flu having 4 months of headstart. This one is MUCH more infectious and much more dangerous.
Agree, the flu is by no means a disease to be underestimated, but countries already do a ton to prevent epidemics of the flu - they already have anti-virals that are somewhat effective and they already have a vaccine that they renew every year(again - because it mutates and slightly different strain circulates in the population every year), they already close schools when there is a jump in cases, etc.. In several years we might have similar success with handling COVID-19... we might have effective anti-virals and we might have a vaccine(although, from what I've read the 18 months is really a very optimistic timeline - usually it takes in the realm of about 10 years to develop a really good vaccine for a new virus. So yeah, some time in the future this might be as dangerous as the flu, right now it's NOT.