Not that I'm bitter or anything

Yipes

Brewing beer is fun and not terribly complicated. 

The mystery to me is why so many beers are almost too bitter to drink. 

Generally to home brew you need to like beer. Beer, however, encompasses hundreds of different ales, lagers, stouts, pilsners, wheat beers, Belgian beers, stouts, etc. 

Virtually all beers are made out of a handful of ingredients: malt of some type, yeast, water and hops. Spices, fruit, chocolate, and other odds and ends can also be added, if that's what you like.

Malting involves tricking barley (usually) into sprouting. The seed produces enzymes that break down starches (the seed's food supply) into simpler sugars that the growing plant will need. The brewer stops this processes after an enzyme in the barley breaks down the starches into maltose, fructose, glucose, and other mono- and disaccharides.

This is done so that the one-celled yeast fungi can consume the sugar and release carbon dioxide and ethanol as waste products. Make sense so far?

Hops

When beer was invented or discovered a long time ago, hops were unknown. The resulting drink probably would have tasted sweet and malty. In the 13th century, we are told, Europeans started to add hops, which to simplify, are flowers of the hops vine. 

Hops added bitterness to balance the sweetness of the malt and acted as a preservative. Specifically hops contain acids which, when boiled, turn into bitter chemicals.

To summarize: you malt barley, boil it with hops, cool it down, add yeast, and in a few weeks you have beer.  If you have added a large amount of hops, you will have extremely bitter beer. That's pretty much what dominates are craft brewing industry(?) these days.

Why drink something that tastes like Paregoric? 

I cannot think of any other widely consumed food or beverage that is predominantly bitter. Bad coffee can be bitter. The human sense of taste has evolved to reject bitter flavors because bitter usually means "poison" or some other unpleasantness.

Bitterness in beer is measured in International Bitterness Units, or IBUs. I'm not making this up. A beer like Coors could have about 10 IBU, give or take.  Below that and what you're drinking doesn't take a lot like beer.

At the other end of the brewing spectrum are concoctions like India Pale Ales, typically from the Northwest, that have IBU levels of 50, 60, 70 or even higher. Since the human sense of taste maxes out at about 50 or so IBUs, all of that extra bitterness is a marketing ploy.

Personally, I would not intentionally brew something that had 60 IBUs. My sense of taste is perhaps closer to 25 to 30, which in some circles would make me a beer wimp. So be it. 

If for some reason you crave bitterness, and assuming you've discussed this with your primary care provider, you simply need to buy some hops online steep them like tea, or maybe boil then, and there you are. No need for yeast, malt or any of that brewing stuff (Mash tuns, sparging, kegging, conditioning, and so on.)

I, on the other hand, like malt. So no "hop bombs" for me. The stuff that I brew barely contains any alcohol, and tastes kind of estery or fruity. 

But infinitely better than a 70-IBU slap in the tongue.