Because it showed up during a contentious election year. Nancy Pelosi and her merry band of criminals needed something,
anything, to try to sink Trump, and they chose Covid, blowing the whole thing out of proportion and trying to paint Trump as a demon king who was somehow responsible, directly or indirectly, for the whole thing. If he wasn't behind the Wuhan lab accident in some way, then he was behind all those deaths of elderly folk in the nursing homes, or he was responsible for not getting a vaccine into production sooner. The vaccines didn't work? Well, no matter---Trump was behind that somehow, too.
They had to paint Trump as the bugaboo, the monster hiding under the bed, the evil cabalist who eats puppies and sacrifices children by the dark of the moon to the great green god of capitalist excess. When Kamala was running against him earlier this year, it was the same thing: "Trump is going to outlaw Social Security! He's going to raise your taxes! He's going to put women who get abortions into concentration camps! He's going to start World War III! Woe! Doom! Disaster! If Trump wins, the world will end!"
If there hadn't been an election in 2020, Covid would have been nothing more than a bad flu season. But Pelosi and the State Organs for the Dissemination of Disinformation and Propaganda (i.e., the mainstream media) inflated it way out of proportion.