Being an old fart, do people actually make a living out of this ? I do Insta for some family stuff, pro cyclists etc
Absolutely they do! However, it is a small minority compared to every plonker giving it a go - like the one you mentioned.
The one's who get the clicks needed for a Marketing Dept. to take notice are generally gorgeous women or real athletes who already have an eager fan base. You need hundreds of thousands of clicks to make a living from it.
It's just another form of Marketing in the digital age. No less of a strategy than TV ads etc.
The issue is can you trust the Influencer? Some will use any means to get clicks which includes lying and 'shock' factor - deliberately being controversial, their real opinion irrelevant. Click-bait.
Some though are genuinely good reviewers who do great work. DC Rainmaker started out this way: Insta, Youtube etc. GCN are Influencers when you watch their Ad content vids. Some retired Pro's do it and get paid by kit sponsors.
Influencers account for a huge amount of Marketing revenue nowadays and can have an enormous effect on what they are promoting. Take photography...on TikTok Influencers went ape about the FujiFilm X100V fixed lens camera. A 'street' camera with retro styling. Result: no-one could buy one for 2 years and they are still, today, back-ordered 6 months. On
eBay they sell for 20-30% over RRP.
Marketers love Influencers and pay them accordingly.