SARS, MERS, and Covid19 are all coronaviruses. Covid19 is a strain that directly came from SARS. SARS did not evaporate. It mutated and evolved which is exactly what viruses do. The link below is a good article that explains the history of coronavirus and talks about how viruses evolve.
WebMD article on the history of coronavirus
This WHO web page has a list of years we had disease outbreaks. They go back to 1965 and include other outbreak diseases like Ebola as well as the Coronaviruses. Just select a year and you can see what the diseases were doing.
WHO timeline of disease outbreaks by year
I know if feels good to rail against the system, but it really isn't hard to look this stuff up. I got these two articles within 3 google searches. If you want to understand diseases and how they work, try looking up information easily provided by WHO, CDC, and WebMD... just to start. Medical and university provided information is likely to be reliable.