There may have "always" been a severe second wave in the past as you say with other epidemics/pandemics, but the level of medical prowess and mass communication that exists today compared to what existed during even the most recent previous pandemic, the 1918 Flu, is far beyond any of our previous capabilities. Modern sanitation and other things we all take for granted now (like the ability to conduct sophisticated scientific research and share insights instantaneously across the globe) also was not a thing in previous pandemics. I would not be so quick to assume COVID-19 will be like the others--at least based on your historical argument. Admittedly I have not studied the reasoning for why some epidemiologists think the second wave could be worse than the first, so I'd be curious to hear any insight on that (in-so-far as staying on topic for this thread).