It's not a surprise to see the rise in antibiotic resistance when antibiotics are used in such a cavalier manner. It's been shown that even sub-lethal exposure to antibiotics can increase existing resistance mechanisms and lead to novel mechanisms as time goes by. And even excluding those things, bacteria naturally harbor resistance genes (for example, a
dysentery strain from WWI was resistant to some modern antibiotics before they were even discovered). It's a constant battle in nature between offense and defense (and most, if not all, of our antibiotics are derived from natural products (stuff found in nature)).
However, the irresponsible use of antibiotics (countries where you can get them sans prescription and using them as growth promoters in animal feed) as well as other environmental sources (like sewage from hospitals and households) are going to pose a major problem over the next several decades, as this will further promote resistance to existing drugs while at the same time, we have a big issue of few antibiotics with novel mechanisms of action being developed and approved.
Happened within the last 100 years; 1/3 of the population of the world got infected but mere 50 to 100 million people died.
https://en.wikipedia.org/wiki/1918_flu_pandemic
I don't think we'll have to worry so much about an epidemic of bacterial infections, but we will be entering an era similar to the pre-antibiotic era, where we don't have any effective drugs to treat infections. As it stands now, ~2 million Americans acquire a resistant infection every year and ~23,000 will die. This costs us tens of billions of dollars in direct and indirect costs, and with the rising prevalence of drug resistance, it's likely we'll see more people die and costs rise further.
Gotta cull the herd somehow.
Why do we have to "cull the herd"?