When humans invented antibiotics and started killing bacteria off en masse, the bacteria knew they had to do something to ensure their survival. We all think our consciousness is the human part of us....but for some, it's actually the bacteria who are running the show.
Lactobacillus is particularly good at controlling the human brain. Lacto-brains have invented delicious foods around the world that serve to both provide breeding grounds for bacteria and spread those bacteria to more people. Yogurt, kefir, sauerkraut, kimchi, sourdough, etc. In more recent years, they've invented their most effective route thus far: probiotics. They've gotten doctors, influencers, and grandmas to recommend them. They let bacteria repopulate people who've taken antibiotics.
Lactobacillus likes to be subtle, but Big Bifido loves plastering its name all over things. The recent popularity of prebiotics is thanks to Bifido. If lactobacillus is a shy dude sitting in the corner, Bifido is a big dude drinking soda and watching TV while he waits for the bus that'll take him to some old lady's intenstines. That's why prebiotic soda are all over the place lately. Bifido loooves soda.
That person you know who keeps talking about pre- and probiotics? That's not the human part talking, that's the bacteria ratatouille-ing them. Probiotics are a trojan horse they're using to reproduce and spread themselves to as many people as possible.