Brewing in monasteries did a lot to keep brewing more of a passion thing than big business. The monks of the Trappist monasteries were largely concerned with just keeping afloat and contributing to charitable works than expanding and making huge piles of cash so their brews don't need to worry about using using malts that are too expensive or things like that. It stopped adjunct malts from showing up in the brews and watering them down.
By the time worldwide distribution became a thing their own styles had been engrained for so long that high quality beer had become a tradition that nobody was willing to leave behind. Sure there are some crappy beers like Stella Artois, but the vast majority of Belgian beer is awesome stuff like Chimay, Corsendonk or Rochefort now.
There's also a pretty big culture there of pairing beer with food and even cooking with beer. Its just deeply engrained in every day life for them, not just as a way to get drunk and be merry but of simply enjoying your breakfast.