For a virus to survive, it has to have hosts. The best way for that to happen is to learn how to better infect without killing the host. That means more potential hosts can be exposed. Rinse, repeat.
… The “COVID-19” we have today is as much like the original strain as today’s Ford Mustang is like the original 1965 pony car. There are a few constants, like four wheels, gas and brake pedals, and a steering wheel. Beyond that, fugeddaboutit. The original had a three-speed stick shift, skinny tires, and drum brakes. The engine had a carburetor, breaker points, and a mechanical distributor to get the spark to each cylinder on time. Its only solid state electronics were transistors in the AM radio. Today’s Mustang looks “sort of” like the original, but the name badge is about where the commonality ends. Most of the other details are radically different.
This is a pretty good description of the comparison between the COVID-19 that led to so much havoc in 2020 and the variants that exist today.
It is well understood by epidemiologists–Each subsequent mutation becomes more infectious but less deadly. It is so well known that it even has a name: Muller’s Ratchet.
People need to get educated.